CN111936417B

CN111936417B - Surface-modified carbon material and method for producing surface-modified carbon material

Info

Publication number: CN111936417B
Application number: CN201980016294.8A
Authority: CN
Inventors: 田原一邦; 户部义人; 石川透; 久保有辉; S·W·N·德菲特; B·E·赫斯; Z·李
Original assignee: National Research And Development Corp Science And Technology Revitalization Organization
Current assignee: National Research And Development Corp Science And Technology Revitalization Organization
Priority date: 2018-03-01
Filing date: 2019-02-28
Publication date: 2023-07-21
Anticipated expiration: 2039-02-28
Also published as: EP3760584A4; JP7158689B2; CN111936417A; WO2019168206A8; US20210070616A1; JPWO2019168206A1; US11993517B2; WO2019168206A1; US20240294383A1; EP3760584A1

Abstract

The present invention relates to a surface-modified carbon material in which a chemical modification group is added to the surface of graphene, wherein one-dimensional periodicity corresponding to a plurality of addition positions of the chemical modification group can be observed in a fourier transform image of a scanning probe microscope image of the surface of graphene. The surface-modified carbon material of the present invention has a band gap, and thus can be used as a sensor and other electronic devices that can be operated under electronic control.

Description

Surface-modified carbon material and method for producing surface-modified carbon material

Technical Field

The present invention relates to a surface-modified carbon material and a method for producing a surface-modified carbon material. Specifically, the present invention relates to a surface-modified carbon material having a chemical modification group periodically added to the surface of graphene or the like, and a method for producing the same.

Background

sp ² Graphene in which carbons are arranged in a honeycomb shape is expected to be used for various applications due to its excellent electrical characteristics, mechanical characteristics, optical characteristics, and thermal characteristics. Among them, graphene is considered to be useful in the field of electronics due to its high conductivity. Thus, researches associated with graphene by universities and research institutions, enterprises, and the like are in active situations.

Graphene is a substance that exhibits half-metallic properties and is a zero-bandgap semiconductor. Therefore, its use directly as an electronic material is limited. However, if the band gap can be properly introduced into graphene, its application in high-performance field effect transistors and small-sized high-sensitivity molecular sensors, which operate at high speed at room temperature, will become possible.

Therefore, numerous methods for introducing band gaps into graphene have been reported. Examples include doping of graphene with electrons or holes by a support substrate, lithographic processing of graphene by light and plasma, micromachining by SPM probes, and defect (sp ³ Carbon), and the like.

Among these methods, the application of chemical modification to graphene has the following advantages: not only the band gap is introduced into graphene, but also the control of fermi level and the control of surface properties are possible due to the electronic or chemical properties of the organic groups added to graphene. Thus, chemical modification of graphene is being studied by heat.

In addition, it is known that, in chemical modification of graphene or the like, an edge portion is more easily chemically modified than an in-plane portion. In the chemical modification of graphene, it is important to control the addition positions of a plurality of active chemical species in the in-plane portion of graphene and to maintain a predetermined order. This is because, if the internal portions of the surface can be chemically modified while maintaining a predetermined order, there is an advantage that a carrier movement system, that is, control of current, can be realized.

First, patent document 1 discloses an invention related to a method of bringing a fluid into contact with a substrate. In the invention, an organic molecular network having a central portion and at least one side arm is provided on a fluid surface in contact with a substrate. Then, two-dimensional molecular sieves formed by adsorbing network molecules on the surface of silicon, metal, pyrolytic graphite (HOPG), or the like are disclosed. Fig. 13 shows a two-dimensional structure 100 formed by the continuous presence and interaction of a basic skeleton 105a and branches 105b of an organic compound on a 6-membered ring planar arrangement 102 of a carbon material.

Next, fig. 14 (a) is a schematic cross-sectional view of a conventional technology according to patent document 2. The prior art of patent document 2 is an invention of forming a modified carbonaceous film on the surface of a substrate 113 such as stainless steel, ceramic, or resin. That is, patent document 2 discloses a modified carbonaceous membrane 110 comprising an sp-containing layer ² Bonded carbon and sp ³ A carbonaceous membrane of bonded carbon, and an organic component (graft chain 111) having a functional group containing a hydrogen atom and an oxygen atom on a surface (6-membered ring planar arrangement 102) and chemically bonded to the surface of the carbonaceous membrane.

Fig. 14 (b) schematically shows a conventional technique according to patent document 3. The electronic device 120 has the following structure on the substrate: the edge-modified graphene film (6-membered ring planar arrangement 122) serves as a channel to which the source electrode 124 and the drain electrode 125 are electrically bonded. In the electronic device 120, a functional group 121 that adsorbs or bonds to a species to be detected is added to the edge of the graphene film, thereby forming an edge-modified graphene sensor. In addition, a method of applying chemical modification not to the edge of a carbon material such as graphene but to the surface of a 6-membered ring planar arrangement has been attempted. Fig. 14 (c) is a photograph showing that after the graphene surface is irregularly chemically modified, the chemical modification groups are mechanically removed by an STM probe, and the carbon surface is exposed to a desired shape. This method is called nano shaving (japanese: nanowielding).

Fig. 15 schematically shows the case where NBD is added as a chemical modification group to the surface of a carbon material. In this example, the substitution reaction in which the aryl group added to the 6-membered ring planar arrangement on the surface of the carbon material is substituted with the aryl radical proceeds continuously, thereby forming a multilayered state. As a result, high density modification and control of addition positions of numerous chemical modification groups in the plane is not achieved for carbon materials.

Thus, in the conventional method, the addition of the active chemical species to graphene occurs unordered, particularly in-plane control of the addition site (sp ³ Carbon positions) are virtually impossible. In addition, it is difficult to closely control the modification rate of the adduct. Several studies have been reported to solve such problems.

For example, non-patent document 1 reports site-selective addition of cyanomethyl radicals to single-layer graphene on Ru (0001) due to interaction between metal and graphene. However, this method cannot control the dimension and period (pitch).

Further, non-patent document 2 reports that addition to graphene occurs by arranging an aryl diazonium salt with a long-chain alkyl group on graphene by self-assembly, and generating aryl radicals by electrochemical reduction. The possibility of periodic modification is then controversial.

The methods of non-patent document 1 and non-patent document 2 are approaches to periodically chemically modified human eyeballs. However, both chemical surface modifications to carbon materials are far from precisely controlled. It is considered that when adding a chemical modification group, the control of the addition position and the control of the modification ratio with high accuracy are insufficient.

In contrast, non-patent document 3 reports a method of synthesizing nanographene and Graphene Nanoribbons (GNRs) from bottom to top by using chemical reactions on a solid substrate and in a solution. The advantage of this approach is that properly sized graphene and GNR can be obtained from the designed precursors. Therefore, in recent years, research on this method has been conducted on normalizing heat. However, the electronic properties and magnetic properties of graphene are greatly dependent on the edge structure, and are greatly different from those of graphene itself. Furthermore, the bandwidth cannot be widened to a certain extent or more.

On the other hand, a method of forming nanopatterns on the surfaces of graphite and graphene by the formation of a self-assembled monolayer physically adsorbed by organic molecules has been reported.

For example, non-patent document 4 reports that a linear alkane forms a layered monomolecular film by self-assembly at the interface between an organic solvent and graphite. However, in this non-patent document 4, there is no disclosure of any idea about chemical modification while periodically controlling the addition position.

Non-patent documents 5 and 6 report a method of forming a self-assembled monolayer on the surface of graphite or graphene by physical adsorption of organic molecules at a solid-liquid interface using a newly synthesized dehydrobenzo [12] rotaene (DBA) derivative. By STM observation, it was confirmed that DBA derivatives formed a cellular molecular arrangement at the interface of the organic solvent and graphite or graphene.

Non-patent document 7 reports experimental results of chemical modification after forming a periodic structure of 6 times rotational symmetry on graphite by the methods of non-patent document 5 and non-patent document 6.

Non-patent document 8 reports a method for producing graphene by a SiC sputtering film formation method. Non-patent document 9 reports a method of forming graphene on a SiO substrate.

In non-patent document 10, sp is periodically introduced into graphene in one dimension ³ In the case of carbon defects, an attempt was made to calculate predictions about the method by which the graphene bandgap can be controlled.

Non-patent document 11 reports a method of adding 3, 5-di-tert-butylbenzene diazonium chloride (TBD) or 4-nitrobenzene diazonium chloride (NBD) as a chemical modification group to the surface of graphene or graphite. A method of partially removing the layer of aryl groups added to the surface of the carbon material in fig. 13 with an STM probe to expose the rectangular region of the carbon surface is shown (see fig. 14 (c)). Further, a method of self-assembling n-fifty molecules and forming two blocks using the rectangular region exposed as a template is shown. In this prior art, the self-assembled n-fifty on the surface of the carbon material can be observed in an orderly arrangement at several adjacent blocks, but in a larger area range, the blocks are arranged in a mosaic shape. Thus, in non-patent document 11, a nano-shaving method using an STM probe is not used to achieve a case where an adduct (chemical modification group) usable in an electronic device is formed in a predetermined alignment state.

Finally, non-patent document 12 reports that defects in graphene can be quantitatively analyzed by raman spectroscopy analysis of different excitation energies.

Prior art literature

Patent literature

Patent document 1: international publication WO2007/118976A2

Patent document 2: japanese patent laid-open No. 2009-61725

Patent document 3: japanese patent laid-open publication No. 2012-247189

Non-patent literature

Non-patent document 1: navaro, j; leret, s.; calleja, F.; stradi, d.; black, a.; bernardo-Gavito, R.; gamnica, m.; granados, D.; vazquez de Parga, A.L.; perez, e.m.; miranda, R.organic Covalent Patterning of Nanostructured Graphene with Selectivity at the Atomic level. Nano Lett.2016,16,355361.

Non-patent document 2: xia, z; leonardi, f.; gobbi, m.; liu, y; bellani, v.; liscio, a.; kovtun, a.; li, R; feng, x.; orgiu, e.; samori, p.; treossi, e.; palermo, V.Electrochemical Functionalization of Graphene at the Nanoscale with Self-Assembling Diazonium salts ACS Nano 2016,10,7125-7134.

Non-patent document 3: cai, j.; ruffieux, p.; jaafar, r.; bieri, m.; braun, t.; blanckenburg, s.; muth, m.; seitsonen, a.p.; saleh, m.; feng, x.; mullen, k.; fasel, R.atom primer Bottom-Up Fabrication of Graphene nanoribs. Nature 2010,466,470-473.

Non-patent document 4: rabe, j.p.; buchholz, S.Commensurability and Mobility in Two-Dimensional Molecular Patterns on Graphite.science 1991,253,424-427.

Non-patent document 5: li, B; tahara, k.; adisoejoso, j.; vanderlinden, w.; mali, k.s.; de Gendt, S.; tobe, y.; de Feyter, S.self-Assembled Air-Stable Supramolecular Porous Networks on graphic. ACS Nano 2013,7,10764-10772.

Non-patent document 6: tahara, k.; adisoejoso, j.; inukai, k.; lei, s.; noguchi, a.; li, B; vanderlinden, w.; de Feyter, S.; tobe, Y.Harnessing by a Diacetylene Unit: a Molecular Design for Porous Two-Dimensional Network Formation at the Liquid/Solid interface chem.Commun.2014,50,2831-2833.

Non-patent document 7: tian Yuanyi bang, development of accurate graphene chemical modification technology based on reactive molecule self-assembly, 95 th spring festival meeting of the Japanese chemical society, 2015, 3 months and 27 days.

Non-patent document 8: three bridges Shi Dian, okadaa Tian Zheng, stadium, upper picchang, middle Lin Longzhi, in order to realize a graphene preparation method (japanese: the Utility line of the Utility line is the best, the Utility line of the Utility line is the most upward and the Utility line of the uniformity is the line of the Utility line, the Utility line of the Utility line is the most upward and the Utility line, and the Utility line is the No. 191 53-58 of the Utility line (SEI line).

Non-patent document 9: novoselov, k.s.; geim, A.K.; morozov, s.v.; jiang, d.; zhang, y; dubonos, s.v.; gridorieva, i.v.; first ov, a.a. electric Field Effect in Atomically Thin Carbon films.science 2004,306,666-669.

Non-patent document 10: lian, J.X.; lherbier, a; wang l.j.; charlie, j. -c; beljone, d.; olivier, Y.electronic Structure and Charge Transport in Nanostripped graphic.J.Phys.chem.C 2016,120,20024-20032

Non-patent document 11: greenwood, j.; phan, t.h.; fujita, y.; li, Z; ivasenko, o.; vanderlinden, w.; van Gorp, h.; frederickx, w.; lu, g.; tahara, k.; tobe, y.; uji-ih; mertens, s.f.l.; de Feyter, S.Covalent Modification of Graphene and Graphite Using Diazonium Chemistry: tunable Grafting and nanomanipulation. ACS Nano 2015,5,5520-5535.

Non-patent document 12: cancoado, l.g.; jorio, a; martins Ferreira, e.h.; stavale, f.; achete, c.a.; capaz, R.B.; moutin ho, m.v.o.; lombardo, a; kulmala, t.s.; ferrari, A.C. quantifying Defects in Graphene via Raman Spectroscopy at Different Excitation energy, nano Lett.2011,11,3190-3196.

Disclosure of Invention

Technical problem to be solved by the invention

The above-described prior art can only implement chemical modification of the edge portion of the carbon material, spot-like chemical modification, or irregular chemical modification of the inside of the surface of the carbon material, which is relatively easy to accomplish.

In other words, new technologies for highly chemical modification required for realizing the new era of device formation have not been achieved yet. That is, it is difficult to add the chemical modification groups to the surface of the carbon material in order. More specifically, it is very difficult to precisely control the in-plane position of the carbon material while adding a chemical modification group to the surface of the carbon material at a high density. Alternatively, it is difficult to chemically modify an area of a certain level or more at a desired modification rate. Thus, it is considered that chemical doping of graphene or the like cannot achieve high control, and it is difficult to prepare a material suitable for a device.

The object of the present invention is to provide a surface-modified carbon material in which chemical modification groups are added to the surface of a carbon material, wherein the addition positions of a plurality of chemical modification groups are controlled in-plane. Specifically, the present invention provides a surface-modified carbon material in which a predetermined order is imparted to addition sites on the surface of the carbon material, and a method for producing the same. Further, an organic compound-carbon material composite, which is an intermediate for producing the surface-modified carbon material, and a method for producing the same are provided.

Technical proposal adopted for solving the technical problems

The present inventors have conducted intensive studies on the type of adducts, reaction conditions, and the like, regarding chemical modification using a film formed by self-assembly of alkane or the like on the surface of a carbon material, for example, graphene or graphite, as a mask.

Then, based on experimental results and theoretical examination, it was found that the addition position of the radical generated by diazonium salt or the like can be controlled to have one-dimensional periodicity or two-dimensional periodicity by causing the addition reaction of the radical generated by diazonium salt or the like to occur in a state where the mask is supported on the surface of the carbon material.

That is, the present invention relates to the following [ form 1] to [ form 28].

Form 1

The surface-modified carbon material is a surface-modified carbon material having a plurality of chemical modification groups on at least a part of the surface of a carbon material selected from the group consisting of graphene, graphite, a glassy carbon film and a film-like thermally decomposed carbon,

wherein one-dimensional periodicity corresponding to a plurality of addition positions of the chemical modifier group is observed in a fourier transform image of the scanning probe microscope image of the surface.

Form 2

The surface-modified carbon material according to [ form 1], wherein the one-dimensional periodicity corresponds to a pitch of 2 to 10nm.

Form 3

The surface-modified carbon material according to [ form 1] or [ form 2], wherein the carbon material is graphene, and Id/Ig of the G-band intensity Ig and the D-band intensity Id in the Raman spectrum of the surface is 0.2 to 5.0.

Form 4

The surface-modified carbon material according to any one of the above [ form 1] and [ form 2], wherein the carbon material is graphite, and Id/Ig of the G-band intensities Ig and the D-band intensities Id in the Raman spectrum of the surface is 0.01 to 0.11.

Form 5

The surface-modified carbon material according to any one of [ form 1] to [ form 4], wherein the chemical modification group is an aryl group.

Form 6

The surface-modified carbon material according to [ form 5], wherein the aryl group is represented by the following formula (1).

[ chemical formula 1]

In the formula (1), R ¹ 、R ² And R is ³ Each independently is alkyl, alkenyl, alkynyl, aryl, OR, COOH, SOOH, SOONH ₂ 、NO ₂ 、COOR、SiR ₃ 、H、F、Cl、Br、I、OH、NH ₂ 、NHR、NR ₂ CN, CONHR or COH (R is alkyl, alkenyl, alkynyl, aryl or halogen substituents thereof).

Form 7

An organic compound-carbon material composite comprising a carbon material, a thin film and a solvent, wherein the carbon material is selected from the group consisting of graphene, graphite, a glassy carbon film and a film-like thermally decomposed carbon, the thin film is composed of a periodic assembly of organic compounds, the surface of the carbon material is covered with the thin film, the solvent is a nonpolar organic solvent or a low-polar organic solvent, and the solvent is disposed on the thin film.

Form 8

The organic compound-carbon material composite according to [ form 7], wherein the thin film comprises a periodic assembly of the organic compound in which a linear alkane having 15 to 80 carbon atoms or a linear alkane derivative having 10 to 80 carbon atoms is arranged in parallel.

Form 9

The organic compound-carbon material composite according to [ form 8], wherein the periodic assembly of the organic compound has polygonal voids.

Form 10

A process for producing a surface-modified carbon material, comprising a step 1 of forming a thin film on the surface of a carbon material with an organic compound, and a step 2 of reacting the surface of the carbon material with a chemical-modifying compound using the thin film as a mask,

characterized in that the organic compound is a linear alkane with 15-80 carbon atoms or a linear alkane derivative with 10-80 carbon atoms,

the carbon material is selected from graphene, graphite, glassy carbon film, and membranous thermally decomposed carbon,

in the step 1, the organic compound is self-assembled on the surface of the carbon material to form a thin film of a film-like periodic assembly exhibiting one-dimensional periodicity,

in the step 2, the chemical modification compound is reacted with the surface of the carbon material at a position of a gap between the periodic assembly.

Form 11

The method for producing a surface-modified carbon material according to [ form 10], wherein the linear alkane or linear alkane derivative is a compound represented by the following formula (2).

[ chemical formula 2]

In the formula (2), X represents H, CH ₃ 、CF ₃ 、CH＝CH ₂ C.ident.CH, aryl, F, cl, br, I, OH, SH, NH ₂ COH or COOH, Y representing CH ₂ 、CF ₂ Ch=ch, c≡c, 2-valent radical formed by removing 2 hydrogen atoms from aromatic hydrocarbon, O, S, NH, CO, COO, CONH, NHCO or NHCHX, Z represents H, CH ₃ Aryl, OH, SH, NH ₂ COH, COOH, COOX, CONH, NHCOX or NHCHX, n is an integer satisfying the condition that the number of carbon atoms in the formula (2) is 15 to 80 in alkane and 10 to 80 in alkane derivative.

Form 12

The method for producing a surface-modified carbon material according to any one of the above [ 10] and [ 11], wherein the thin film is a layered monolayer.

Form 13

The method for producing a surface-modified carbon material according to any one of [ 10] to [ 12], wherein the chemical modification compound is a compound represented by the following formula (3).

[ chemical formula 3]

In the formula (3), R ¹ 、R ² And R is ³ Each independently is alkyl, alkenyl, alkynyl, aryl, OR, SOOH, SOONH ₂ 、COOH、NO ₂ 、COOR、SiR ₃ 、H、F、Cl、Br、I、OH、NH ₂ NHR, CN, CONHR or COH (R is alkyl, alkenyl, alkynyl or aryl), Z is a halogen atom, BF ₄ 、BR ₄ Or PF (physical pattern) ₆ (R ₄ Is alkyl, alkenyl, alkynyl, aryl, or a halogen substituent thereof).

Form 14

A method for producing a surface-modified carbon material by electrochemically reacting a chemical modification compound with a carbon material using an electrochemical cell comprising a working electrode, a counter electrode, a reference electrode, and an aqueous electrolyte solution,

wherein the working electrode is made of a carbon material selected from the group consisting of graphene, graphite, a glassy carbon film, and film-like thermally decomposed carbon,

as the aqueous electrolyte solution, an aqueous solution containing the chemical modification compound is used,

a liquid medium containing a compound exhibiting periodic self-assembly is disposed between the working electrode and the aqueous electrolyte solution, and the aqueous electrolyte solution and the liquid medium are non-miscible with each other.

Form 15

The method of producing a surface-modified carbon material as defined in [ form 14], wherein the compound exhibiting periodic self-assembly is a linear alkane having 15 to 80 carbon atoms or a linear alkane derivative having 10 to 80 carbon atoms.

Form 16

The method for producing a surface-modified carbon material according to [ 15], wherein the linear alkane or linear alkane derivative is a compound represented by the following formula (2).

[ chemical formula 4]

Form 17

The method for producing a surface-modified carbon material according to any one of [ 15] and [ 16], wherein the concentration of the alkane or the linear alkane derivative in the liquid medium is 1. Mu. Mol/L or more.

Form 18

The method for producing a surface-modified carbon material as defined in [ form 14], wherein the compound exhibiting periodic self-assembly property is a dehydrobenzo [12] rotaene derivative.

Form 19

The method for producing a surface-modified carbon material according to any one of [ 14] to [ 18], wherein the liquid medium is obtained by dissolving the compound exhibiting periodic self-assembly in a nonpolar organic solvent or a low-polarity organic solvent.

Form 20

The method for producing a surface-modified carbon material according to [ form 19], wherein the nonpolar organic solvent or the low-polar organic solvent is one or more selected from the group consisting of fatty acids, alkyl-substituted benzenes, alkanes having less than 20 carbon atoms, alkanols, dialkyl ethers, halogenated hydrocarbons and aromatic hydrocarbons.

Form 21

The method for producing a surface-modified carbon material according to any one of [ 14] to [ 20], wherein the concentration of the chemical modification compound in the aqueous electrolyte solution is 0.2 to 10.0 mmol/L.

Form 22

The method for producing a surface-modified carbon material according to any one of [ 10] to [ 21], wherein the chemical modification compound is a compound represented by the following formula (3).

[ chemical formula 5]

Form 23

The surface-modified carbon material is a surface-modified carbon material having a plurality of chemical modification groups on at least a part of the surface of a carbon material selected from the group consisting of graphene, graphite, a glassy carbon film, and a film-like thermally decomposed carbon,

Characterized in that the surface has a two-dimensional periodicity of 5-15 nm for each partition, the two-dimensional periodicity corresponding to a plurality of addition positions of the chemical modifier groups being provided in a Fourier transform image of a scanning probe microscope image of the surface ² When the area of the (c) is divided, the proportion of the total number of the divided regions in which the chemical modification group is present to the total number of the divided regions is 70% or more.

Form 24

The surface-modified carbon material according to [ form 23], wherein the proportion is 90% or more.

Form 25

A field effect transistor comprising the surface-modified carbon material according to any one of [ form 1] to [ form 6], [ form 23] or [ form 24 ].

Form 26

A sensor comprising the surface-modified carbon material according to any one of [ form 1] to [ form 6], [ form 23] or [ form 24 ].

Form 27

A light-emitting element comprising the surface-modified carbon material according to any one of [ form 1] to [ form 6], [ form 23] or [ form 24 ].

Form 28

A catalyst comprising the surface-modified carbon material according to any one of [ form 1] to [ form 6], [ form 23] or [ form 24 ].

Effects of the invention

The present invention provides a surface-modified carbon material comprising a carbon material selected from the group consisting of graphene, graphite, a glassy carbon film, and a film-like thermally decomposed carbon, wherein a plurality of addition sites of the chemical modification groups have a predetermined periodicity as a whole. Therefore, the surface-modified carbon material of the present invention has advantages in that it can control the movement of carriers (i.e., current). Alternatively, when forming an electronic device, a change in carrier movement corresponding to an external environmental change may be perceived indirectly.

The method for producing a surface-modified carbon material of the present invention can controllably add a chemical modification group to the surface of a carbon material, and can produce a surface-modified carbon material having periodicity in addition positions of a plurality of chemical modification groups. The glassy carbon film is a film-like object of a substance having glass and ceramic properties, and its constituent substances are all sp ² And (3) carbon. Examples of the thermally decomposed carbon film include carbon films having a film thickness of about several μm, which are decomposed at a high temperature of about 1000 ℃. It is known that the manufacturing process can be varied to tailor its layer structure and internal structure. Next, as a representative example of the carbon material in the present invention, experiments and the like of examples were performed using graphene or graphite as a material.

In the method for producing a surface-modified carbon material of the present invention,by appropriately adjusting the molecular length and shape of an alkane or the like used as a mask, sp arranged with a predetermined period (for example, one-dimensional periodicity, two-dimensional periodicity, or the like) can be introduced into graphene or the like ³ And (3) carbon.

The method for producing a surface-modified carbon material of the present invention breaks the limitation of conventional micromachining by a lithographic method. Is capable of realizing very fine processing at a level close to a molecular level, and introducing sp into graphene or the like at various widths according to a molecular length of alkane or the like used as a mask ³ New technology of carbon.

Drawings

[ FIG. 1 (a)]FIG. 1 (a) is an STM observation image of a surface-modified carbon material formed with a film exhibiting one-dimensional periodicity according to the present invention. The image of the lower right part of each STM observation image (quadrangular frame) is a fourier transform image of the STM observation image. Photograph A is C ₅₀ H ₁₀₂ In the case of (C), photo B is C ₄₀ H ₈₂ In the case of (C), photo C is C ₃₀ H ₆₂ Is the case in (a).

FIG. 1 (b) is an explanatory diagram of STM observation in a liquid.

FIG. 1 (c) A schematic view showing a state in which the surface of a carbon material is covered with a thin film composed of an alkane as an example of an organic compound.

FIG. 1 (d) is a schematic view showing a state in which an adduct is added to grooves covering the arrangement of organic compounds on the surface of a carbon material to form a surface-modified carbon material.

Fig. 1 (e) is a photograph (low magnification) showing the surface of the surface-modified carbon material according to the present invention.

Fig. 2 (a) is a schematic diagram showing a surface-modified carbon material obtained by a conventional method for producing a surface-modified carbon material.

Fig. 2 (b) is a schematic view showing a surface-modified carbon material obtained by the method for producing a surface-modified carbon material of the present invention.

Fig. 2 (c) is a schematic view showing a surface-modified carbon material (high density type) obtained by the method for producing a surface-modified carbon material of the present invention.

Fig. 3 (a) is a photograph showing the appearance of an example of an electrochemical cell used in the method for producing a surface-modified carbon material of the present invention. The sub-image (O) is a photograph seen from obliquely above, the sub-image (S) is a photograph seen from the lateral direction, and the sub-image (T) is a photograph seen from directly above.

Fig. 3 (b) is a schematic cross-sectional view showing the use states of the electrochemical cells used in the examples and comparative examples.

Fig. 3 (c) is a schematic cross-sectional view for showing the dimensions of the various parts of the electrochemical cell.

Fig. 3 (d) is an experimental result relating to the prior art (reference diagram from non-patent document 11), and is a voltage-current characteristic diagram according to the CV method when NBD and TBD are used as chemical modification groups. The case where the sub-picture (1) is NBD and the case where the sub-picture (2) is TBD. The first scanning wave and the second scanning wave are arranged from bottom to top.

Fig. 3 (e) is a graph of raman spectrum when NBD is used as a chemical modifying group, which is an experimental result related to the prior art (reference diagram from non-patent document 11).

Fig. 3 (f) is an experimental result relating to the prior art (reference diagram from non-patent document 11), and is a raman spectrum graph when TBD is used as a chemical modifying group.

Fig. 3 (g) is an explanatory diagram showing a method of surface chemical modification of a carbon material by cyclic voltammetry, which is an experimental result related to the prior art (refer to fig. 11). The graph (1) is a graph showing the waveform of the applied voltage when scanning by the CV method. Panel (2) is a graph showing the Raman spectrum prior to scanning by the CV method. The graph (3) is a raman spectrum graph after scanning by CV method. The first scanning wave, the second scanning wave and the third scanning wave are arranged from bottom to top.

FIG. 4 (a) is an explanatory view schematically showing the structure of a dehydrobenzo [12] rotaene derivative.

FIG. 4 (b) is an explanatory view showing a hexagonal periodic structure (assembly) composed of 6 molecules of a dehydrobenzo [12] rotaene derivative.

Fig. 4 (c) is an explanatory view showing a state in which a plurality of dehydrobenzo [12] rotarene derivative molecules are assembled in a hexagonal structure and formed into a thin film attached to the surface of a carbon material.

Fig. 4 (d) is an explanatory diagram showing a surface-modified carbon material obtained by periodically adding chemical modification groups to the surface of the carbon material in two dimensions.

FIG. 4 (e) is a diagram showing the relationship between the steps of electrochemical treatment of [ A ], self-assembled monolayer (alkane thin film) of [ B ], nanopatterning of [ C ] with covalent bond, and surface modification of [ D ] with an adduct in the production method of the present invention.

Fig. 5 (a) is a schematic plan view of a basic form (an example) of an assembly having a two-dimensional periodic structure according to the present invention.

FIG. 5 (b) is an explanatory diagram showing the relative sizes of the individual units of an assembly of dehydrogenated benzo [12] rotarene derivatives on the surface of a carbon material in an observation image of STM.

Fig. 5 (c) is a flowchart showing a process for producing the surface-modified carbon material of the present invention.

Fig. 5 (d) ] fig. 5 (d) is a schematic plan view of an electronic device 90F (uniform pitch) of other structural example 1 using a surface-modified carbon material according to the present invention.

Fig. 5 (e) is a schematic plan view of an electronic device 90P (irregular pitch type) of other structural example 2 using the surface-modified carbon material according to the present invention.

Fig. 6 (a) is a schematic view showing a case where chemical modification groups have one-dimensional periodicity arranged on the surface of a carbon material.

Fig. 6 (b) is a schematic diagram showing a case where chemical modification groups are arranged on the surface of a carbon material with a two-dimensional periodicity (quadrangular lattice arrangement).

Fig. 6 (c) is a schematic diagram showing a case where chemical modification groups are arranged on the surface of a carbon material with a two-dimensional periodicity (honeycomb structure).

Fig. 6 (d) is a schematic plan view of a basic form of an electronic device 300 in which electrodes are formed on both ends of a carbon material (GNR) processed into a fine sheet shape by modification with a surface modification group having one-dimensional periodicity.

Fig. 6 (e) is a schematic plan view of a basic form of an electronic device 400 in which electrodes are formed on both ends of a surface-modified carbon material (GNR) obtained by modifying a carbon material processed into a fine sheet shape with a surface-modifying group having a two-dimensional periodicity.

Fig. 6 (f) is a schematic cross-sectional view of an electronic device 500 used as a sensor in which electrodes are formed at both ends of the surface-modified carbon material of the present invention.

Fig. 6 (g) is a schematic cross-sectional view of an electronic device 600 in which electrodes are formed at both ends of a surface-modified carbon material of the present invention and used as an element structure having a bottom gate.

FIG. 7 shows a cyclic voltammogram obtained in example 1-1. The first scanning wave, the second scanning wave, the third scanning wave, the fourth scanning wave and the fifth scanning wave are arranged from bottom to top. Subgraph (b) and (c) are STM observed images obtained in example 1-1, and the upper right image of subgraph (b) is a Fourier transform image of the STM observed image. Sub-graph (d) is the Raman spectrum obtained in example 1-1. Sub-image (e) is an enlarged image of the fourier transform image.

FIG. 8 shows an STM observation image obtained in example 1-2. Sub-plot (b) is a Fourier transform image of the STM observation image obtained in examples 1-2.

FIG. 9 shows the STM observation image obtained in examples 1 to 3. The upper right image of sub-image (a) is a fourier transform image of the STM observation image, and sub-image (b) is an enlarged image of the fourier transform image.

FIG. 10 shows the cyclic voltammogram obtained in examples 1-4. The first scanning wave, the second scanning wave, the third scanning wave, the fourth scanning wave and the fifth scanning wave are arranged from bottom to top. Subgraphs (b), (c) and (f) are STM observations obtained in examples 1-4. Subgraph (d) and (e) are raman spectra obtained in examples 1 to 4. Subgraph (g) is a fourier transform image of the STM observation image obtained in examples 1 to 4.

Fig. 11 is data corresponding to examples 1 to 5, with subplot (a) being cyclic voltammograms obtained in examples 1 to 5, subplot (b), subplot (c) and subplot (d) being STM observations obtained in examples 1 to 5. The sub-graph (a) is a first scanning wave, a second scanning wave, a third scanning wave, a fourth scanning wave and a fifth scanning wave from bottom to top. The upper right image of sub-figure (b) is the fourier transform image of the STM observation image.

FIG. 12A is a cyclic voltammogram obtained in comparative example 1-1. The first scanning wave, the second scanning wave, the third scanning wave, the fourth scanning wave and the fifth scanning wave are arranged from bottom to top. Subgraph (b) is the STM observation image obtained in comparative example 1-1. The upper right image of sub-figure (b) is the fourier transform image of the STM observation image. The raman spectrum obtained in comparative example 1-1 is shown in the drawing (c), and the fourier transform image is shown in the drawing (d).

Fig. 13 is a schematic plan view showing a state in which an organic compound assembly is formed on graphite as the conventional art of patent document 1.

Fig. 14 (a) is a schematic plan view showing the state in which a graft chain is formed on a carbonaceous membrane as in the prior art related to patent document 2.

Fig. 14 (b) is a schematic plan view showing a case of chemically modifying the edges of graphene using a graphene sensor in which graphene having a zigzag shape as a whole is used as a sensing site, as a conventional technique according to patent document 3.

Fig. 14 (c) is a photograph and explanatory diagram of an example of exposure of a predetermined region by nano-shaving a HOPG surface previously subjected to random chemical modification of a plurality of 3, 5-TBDs using an STM probe, as cited from non-patent document 11.

Fig. 15 is a schematic view showing the case where NBD is added as a chemical modification group to the surface of a carbon material in a manner of forming a plurality of layers as in the prior art.

FIG. 16A schematic structural view of an example of a single unit using a known organic compound (H3 BTB) applicable to the present invention.

FIG. 17 (a) is an STM observation image (sub-graph (a)) obtained by chemically modifying the surface of a carbon material with H3 BTB. Sub-graph (b) is a cyclic voltammogram. The first scanning wave and the second scanning wave are from bottom to top. Sub-plot (c) is raman spectral data and sub-plot (d) is a fourier transformed image.

FIG. 17 (b) shows an STM observation image (sub-image (a)) and a Fourier transform image (sub-image (b)) obtained by chemically modifying the surface of a carbon material with DBAOC 6.

FIG. 18 is an explanatory diagram of a modification of the alkyl side chain length of DBA as a single unit of an assembly having hexagonal voids.

FIG. 19 is a schematic diagram of the structures of DBAOC4 to DBAOC10 that can form an assembly.

Fig. 20 is an STM observation image and a fourier transform image showing periodicity of DBAOC10, DBAOC8, and DBAOC 6.

FIG. 21 is a schematic view showing the structure of a known group of organic compounds which can be applied to the present invention. The sub-graph (a) is an explanatory diagram showing names and chemical formulas of individual units having different branch lengths in the group of DBA-DA compounds as examples of the organic compounds other than DBAOCn. The sub-graphs (b) to (e) are schematic structural diagrams of 4 organic compounds in DBA-DA12,12 to DBA-DA32, 33.

Fig. 22, sub-graph (a) is a wide-area STM observation image. Subgraph (b) is STM observation image. And the sub graph (c) is a schematic structural diagram of an assembly formed by assembling six organic compounds (single units).

Fig. 23 is an explanatory diagram showing a structure of other organic compound groups which can form a two-dimensional periodic structure. N in the structural formula is any integer.

Fig. 24 is an explanatory view of a case of a star-shaped regular hexagon as an example of a two-dimensional periodic structure. Subgraph (a) is a chemical structural formula showing an organic compound constituting a single unit, subgraph (b) is an STM observation image showing a thin film, and subgraph (c) is an explanatory diagram showing the positions of cage structures in the STM observation image.

FIG. 25 is an explanatory view showing a compound that can form an assembly of a two-dimensional periodic structure having a double cyclic structure.

Fig. 26 (a) is a diagram showing a dextrorotatory (CW) structure in an assembly of DBAOC6 assembled with 6 molecules on a surface, and fig. 26 (b) is a diagram showing a levorotatory (CCW) structure in an assembly of DBAOC6 assembled with 6 molecules on a surface.

Fig. 27 (a) is an STM image beside the area boundary of the honeycomb structure formed by DBAOC6, and fig. 27 (b) is a fourier transform image of the STM image beside the area boundary of the honeycomb structure formed by DBAOC 6.

FIG. 28A is an STM image of a modified graphite surface obtained by chemically modifying graphite with an aryl group using DBAOC6 as a template, and FIG. 28B is a Fourier transform image of a modified graphite surface obtained by chemically modifying graphite with an aryl group using DBAOC6 as a template.

FIG. 29 is a diagram showing the surface-facing arrangement of 2-molecule DBAOC 6.

Detailed Description

The surface-modified carbon material of the present invention is a surface-modified carbon material obtained by adding a plurality of chemical modification groups to at least a part of the surface of a carbon material selected from the group consisting of graphene, graphite, a glassy carbon film and a membranous thermally decomposed carbon, and is a one-dimensional periodic surface-modified carbon material in which a plurality of addition positions corresponding to the chemical modification groups are observed in a fourier transform image of a scanning probe microscope image of the surface. In general, it is known that the fourier transform image does not have periodicity, and this means that the fourier transform image is a non-characteristic optical wheel pattern.

The surface-modified carbon material of the present invention is a carbon material selected from graphene, graphite, glassy carbon film, and membranous thermally decomposed carbon. The carbon material is a carbon material in which a plurality of chemical modification groups are added to at least a part of the surface of graphene or the like so as to exhibit a predetermined periodicity.

Graphene and graphite are of sp ² Bonded carbonCarbon material having a hexagonal lattice structure in which atoms are bonded in a honeycomb form. That is, the surface-modified carbon material of the present invention is produced by reacting a chemical modification group with sp constituting the carbon material ² And (3) bonding carbon atoms to obtain the novel carbon material. Further, as the base film of the carbon material, for example, siO may be used ₂ And SiC and the like.

In the surface-modified carbon material of the invention, the carbon atom bonded by the chemical modification group is sp ³ And a carbon atom is bonded. In other words, the surface-modified carbon material of the present invention is a material comprising sp ² Sp is introduced into the surface of a carbon material such as graphene formed by bonding carbon atoms ³ A carbon material obtained by bonding carbon atoms. From the viewpoints of graphene and graphite whose surfaces are chemically modified, the graphene material contains sp ³ A "defective" carbon material bonded to a carbon atom.

In the surface-modified carbon material of the present invention, periodicity due to the addition position of a plurality of the above-mentioned chemical modification groups, in other words, periodicity corresponding to sp, is observed in one-dimensional direction in a Fourier transform image of an observation image of a scanning probe microscope (SPM: scanning Probe Microscope) on the surface thereof ³ Periodicity of bonding carbon atoms or defects.

By "periodicity is observed in one dimension" is meant that in the fourier transform image, the vector direction in which periodicity occurs is only one direction, not more than two directions. In the present invention, the term "periodicity is observed in two dimensions" means that the vector direction in which periodicity occurs in the fourier transform image is two or more directions. In the present invention, as a direction criterion in determining periodicity, for example, it is considered that a carbon material having a surface chemically modified can be used as a longitudinal direction of a channel in forming an electronic device.

In the image obtained by fourier transforming the STM observation image, a light spot corresponding to periodicity in the sample appears. For example, if the chemical modification in the sample is one-dimensional periodic, both the X-axis and Y-axis of the image can be used as the standard axis of the Fourier transform image, but assuming the X-axis is used, a strong spot is observed at a symmetrical position on the X-axis with respect to its origin. If a flare with a low luminance is additionally present, a period of 2 times or 3 times is found at a position distant from the origin in the vector direction connecting the flare with a high luminance from the origin of the fourier transform image.

In the case of two-dimensional periodicity, a spot group having symmetry is generally observed on each of the X-axis and the Y-axis with the origin as the center. When a surface of a carbon material is modified using a mask in which periodic assemblies are arranged continuously on a plane as units, a rotationally symmetrical spot centered on an origin is observed in a fourier transform image of an STM image thereof. For example, the mask is honeycomb-shaped, and in a fourier transform image of an STM observation image corresponding to a carbon material to which surface modification is applied, it is necessary to observe, as a basic unit thereof, at least a flare at the vertex of a hexagon centered at the origin.

In addition, when two intersections are strongly developed on the X-axis and a light intersection is observed at a position of the two-dimensional periodicity, it is determined that the two-dimensional periodicity is satisfied as a whole. The most basic examples are shown in table 1 below. In addition, in the case of the two-dimensional periodic arrangement of the honeycomb shape, the spot group of the fourier transform image has 60 degree rotational symmetry, but there is a difference of 30 degrees in the appearance of the spots in the fourier transform image depending on whether the six-membered ring arrangement of the carbon material is set to an armchair (armchair) structure or a zigzag (zig) structure along the channel. The dashed arrows in table 1 indicate the channel direction.

TABLE 1

In the present invention, the applicable scanning probe microscope is not particularly limited, and examples thereof include a scanning tunneling microscope (STM: scanning Tunneling Microscope) and an atomic force microscope (AFM: atomic Force Microscope). In the following examples, the carbon surface was observed using a Scanning Tunneling Microscope (STM).

STM is a type of SPM that detects tunneling current flowing even in a noncontact manner by tunneling effect acting at a very close distance between a probe and a sample. The schematic structure is shown in fig. 1 (b). A voltage may be applied to the sample 162 carried on the conductive substrate 161, and the surface thereof may be observed three-dimensionally by the probe 160. The sharper the probe used, the higher the resolution. For the observation at the atomic level, usually single-atom or single-molecule probes are used.

STM observations can achieve atomic resolution in ultra-high vacuum, and molecular resolution even in the atmosphere or in liquids. In the present invention, STM is used for obtaining a solid space image such as a surface state or an atomic structure of a carbon material with high spatial resolution, and further for determining a position of an adduct at a surface of the carbon material and detecting an arrangement state of the adduct on the entire surface.

In the present invention, in order to chemically modify the surface of a carbon material, a thin film formed of an organic compound that covers the surface is used. The film is used as a mask, and chemical modification groups are reacted with the surface of the carbon material at the positions of the voids of the film. As a result, the addition position of the chemical modification group can be controlled in-plane. In the present invention, a film in which voids (grooves) or an arrangement of a plurality of voids existing in a face exhibits one-dimensional periodicity or two-dimensional periodicity can be used.

With respect to one-dimensional periodicity, the period between the molecular columns constituted by the thin film corresponds to a one-dimensional period, which can be read from the STM observation image. In contrast, the period in the parallel direction of the molecular columns is irregular. I.e. there is a period in only one vector direction. On the other hand, two-dimensional periodicity finds periodicity in more than two vector directions.

The fourier transform image is an image obtained by performing STM observation on the surface of the surface-modified carbon material and fourier transforming the obtained observation image. Periodicity corresponding to the addition positions of the plurality of chemical modification groups in the surface-modified carbon material can be confirmed by fourier transform image.

STM observations were made by the following procedure. STM observations were made on the surface-modified samples using a scanner capable of observing the first order (step) of graphite in the range of about 100pm to 500pm at the interface between the organic solvent and graphite (carbon material) used in the electrochemical method described below. Regarding the obtained STM image, slope correction was performed by SPIP image analysis software (registered trademark), and then FFT processing was performed to evaluate the periodicity of the adduct. The FFT processing does not need to set a threshold value for detecting a flare. The period of the relatively high portion (i.e., the aryl portion added to the surface of the carbon material) can be reliably detected.

In this case, in the following examples, observations were made under the conditions that the height of alkane used as a template was about 50pm and the height of aryl was about 200 to 250 pm. In other embodiments, where DBA is used as the template, the measurement may be performed with the DBA having a height of about 50pm and the aryl having a height of about 200 to 250 pm.

Alternatively, in the case where it is necessary to detect each adduct, a method of detecting a component at a position higher than the height of template molecules such as alkane and DBA and the height of the surface of the carbon material may be considered. Further, in the case where an effective value of the difference in height between the chemical modification group and the template is required, for example, the apparent height as a threshold value at the time of measurement may be set to 100pm or more by using the above-mentioned calibrated scanner. In the case of applying the surface finish by the shaving method described below, the surface finish is a level difference from the surface of the carbon material (graphite) itself. For example, 500pm to 2000pm is assumed by a calibrated scanner (see non-patent document 11)

The periodicity observed in the fourier transform image is, for example, a pitch of 2 to 10nm in the case of a one-dimensional periodic structure. Fig. 1 (a) is a fourier transform image showing, in contrast, an STM observation image of a thin film formed with three kinds of alkanes having one-dimensional periodicity according to the present invention, and an image of a lower right portion of each STM observation image (quadrangular frame) is an STM observation image.

In FIG. 1 (a), STM observation image A was C as the organic compound used ₅₀ H ₁₀₂ Is the case in (a). STM observation image B is C ₄₀ H ₈₂ Is the case in (a). STM observation image C is C ₃₀ H ₆₂ Is the case in (a).

Further, the periodicity in each STM observation image was 6.8mm, 5.8mm, and 4.1mm in the order of STM observation image A, B, C, respectively. That is, the length of one side of the membrane unit (block) is first determined based on the number of carbons of the organic compound (alkane) used and the physical dimension (molecular length) of the linear chain. Then, it is considered that one-dimensional periodicity among the plurality of chemical modification group arrangements is formed in conjunction with the arrangement of the blocks and the positions of the grooves.

That is, in one form of the surface-modified carbon material of the present invention, the addition positions of a plurality of chemical modification groups in the surface-modified carbon material, in other words, sp ³ The bonded carbon atoms or defects are observed in the fourier transform image in one dimension with a period of 2 to 10 nm. The periodicity is preferably 2 to 9nm. The validation of periodicity from the fourier transformed image is detailed in the embodiments.

The method for producing the surface-modified carbon material having such periodicity is described below.

The chemical modification group is not particularly limited as long as it can be added to the surface of a carbon material such as graphene, but an aryl group is preferable in view of convenience in confirming the above periodicity. Examples of the aryl group include a group represented by the following formula (1).

[ chemical formula 6]

In the formula (1), R ¹ 、R ² And R is ³ Each independently is alkyl, alkenyl, alkynyl, aryl, OR, SOOH, SOONH ₂ 、COOH、NO ₂ 、COOR、SiR ₃ 、H、F、Cl、Br、I、OH、NH ₂ NHR, CN, CONHR or COH, R is alkyl, alkenyl, alkynyl, aryl or a halogen substituent thereof. Examples of the alkyl group include methyl, ethyl, propyl, butyl, and the like.

In the surface-modified carbon material of the present invention, G-bands and D-bands preferably occur in raman spectra for the surface thereof. Further, in the surface-modified carbon material in which a surface-modifying group is added to at least a part of the surface of graphene, the Id/Ig of the G-band intensity Ig and the D-band intensity Id is preferably 0.2 to 5.0, more preferably 0.3 to 4.0, and even more preferably 0.5 to 3.0.

In addition, non-patent document 10 describes sp in graphene ³ Carbon density (distance) versus Id/Ig value. For example, if sp ³ The Id/Ig value was 2.9 when the distance between carbons was 5 nm. Furthermore, it is also described that if the modification is made above a certain density, the increase in Id/Ig value will cease.

In the surface-modified carbon material having surface-modifying groups added to at least a part of the surface of graphite, the G-band strength Ig and the D-band strength Id/Ig are preferably 0.01 to 0.11, more preferably 0.01 to 0.08, and still more preferably 0.01 to 0.06. The surface-modified carbon material with Id/Ig in the above range has enough chemical modification groups and can be effectively utilized as a novel carbon material. In addition, even when the chemical modification group (adduct) added to the surface of the carbon material in the present invention is exposed to an ambient temperature of about 200 ℃, the addition state thereof can be maintained.

As an example of the method for producing a surface-modified carbon material of the present invention, there is a method in which an alkane or an alkane derivative is attached to at least a part of the surface of a carbon material selected from the group consisting of graphene, graphite, a glassy carbon film and a membranous thermally decomposed carbon as a thin film having a one-dimensional periodic structure, and a chemical modification group is added to the surface by reacting a chemical modification compound with the carbon material using the thin film as a mask.

As the alkane or alkane derivative, a linear alkane having 15 to 80 carbon atoms, preferably 16 to 60 carbon atoms, or a linear alkane derivative having 10 to 80 carbon atoms, preferably 12 to 60 carbon atoms is preferably used.

The chemical modification compound in the present invention means a group of compounds having a reactive group covalently bonded to carbon constituting a six-membered ring planar arrangement. Furthermore, it is important that chemical modification compounds do not form chemical bonds to each other to form layers. In order to achieve dense chemical modification, chemical modification compounds are preferably relatively small molecular structures with steric symmetry that are not complex in structure. The examples and comparative examples described below each use one organic compound, but a plurality of compounds may be used at the same time as long as the effect of the intended chemical modification is not lost.

The term "film having a one-dimensional periodic structure" refers to a film comprising three or more film units (blocks) each formed by arranging molecules of a linear alkane or an alkane derivative in parallel. In the film, the molecular chains such as alkane contained in each block are aligned with the molecular chains such as alkane contained in the adjacent block.

Then, at this time, the blocks are formed so as to be arranged at intervals. Thus, the molecular chains such as alkanes are periodically arranged in the molecular chain direction (i.e., in one-dimensional direction). The film may be a monolayer of an alkane or an alkane derivative, or may be a multi-molecular film in which two or more layers are laminated. The monolayer is preferable in view of easiness of reaction of the chemical modification compound with the carbon material. The monolayer is, for example, a layered monolayer.

In order to align straight chain molecules such as alkanes in a predetermined alignment, the alignment of molecular chains capable of self-assembly in the flow direction thereof can be naturally induced by inducing extremely small flow in a solution containing alkanes or the like. Alternatively, a template may be formed in advance by physically processing the surface shape outside the region to be formed into a rectangle or the like, whereby the formation of a block of molecular chains can be induced along the inner shape of the template.

The straight-chain alkane having 15 to 80 carbon atoms which can be used in the present invention is not particularly limited, and any alkane can be used. Specifically, the catalyst is triacontane having a carbon number of 30, tetradecane having a carbon number of 40, and fifty alkanes having a carbon number of 50. In the case of a linear alkane having 14 or less carbon atoms, the adsorption force is weak, and in many cases, it is not preferable to use a monolayer thereof as a mask, and periodic modification is hardly expected. If the alkane is a linear alkane having 81 or more carbon atoms, the adsorption force is too strong, and in many cases, the modification rate is lowered.

In the alkane derivative, even if the carbon number is less than 15, a strong intermolecular force may be obtained depending on the kind of the functional group, and a monomolecular film suitable for a mask may be produced, so that if the carbon number is 10 or more, there is a compound that can be used. The linear alkane having 15 to 80 carbon atoms and the linear alkane derivative having 10 to 80 carbon atoms can be represented by, for example, the following formula (2).

[ chemical formula 7]

X represents H, CH ₃ 、CF ₃ 、CH＝CH ₂ C.ident.CH, aryl, F, cl, br, I, OH, SH, NH ₂ COH or COOH, Y representing one or more CH's present in the molecule ₂ 、CF ₂ Ch=ch, c≡c, aryl, O, S, NH, CO, COO, CONH, NHCO or NHCHX, Z represents one or more H, CH present in the molecule ₃ Aryl, OH, SH, NH ₂ COH, COOH, COOX, CONH, NHCOX or NHCHX.

n is an integer satisfying the condition that the number of carbon atoms in the formula (2) is 15 to 80 in the alkane and 10 to 80 in the alkane derivative. In the formula (2), Y's having n numbers may be the same or different, and Z's having n numbers may be the same or different.

The chemical modification compound is a compound that reacts with the surface of a carbon material such as graphene to induce the chemical modification group to be added to the surface. The chemical modification compound is not particularly limited as long as it can react with a carbon material such as graphene and the chemical modification group is added to the surface of the carbon material such as graphene. In this case, an aryl compound is preferable in view of convenience in confirming the periodicity of the chemical modification group to be added. Examples of the aryl compound include compounds represented by the following formula (3).

[ chemical formula 8]

Specific examples of the compound represented by the above formula (3) include 3, 5-di-t-butylbenzene diazonium chloride (TBD), 3,4, 5-trialkoxybenzene diazonium chloride, and 4-nitrobenzene diazonium chloride (NBD).

The reaction of TBD with graphene and graphite proceeds, for example, as follows.

[ chemical formula 9]

First, TBD is reduced and aryl radicals are generated. The aryl radical is added on the surface of carbon materials such as graphene. By this reaction, a surface-modified carbon material having a chemical modification group induced by TBD added to the surface of a carbon material such as graphene can be obtained. The carbon atom to which the TBD-induced chemical modification group is added is sp ³ And a carbon atom is bonded.

Fig. 1 (c) and (d) are schematic views showing a method for producing the surface-modified carbon material. Fig. 1 (c) shows a state in which a linear alkane 2 is added to the surface of a material 1 which is graphene or graphite carbon as a thin film 3 having a one-dimensional periodic structure.

In fig. 1 (c), the film 3 is composed of three blocks (film units). In the film 3, the linear alkane 2 is arranged in parallel to form a block. Then, the blocks are arranged at intervals so that the molecular chains of the linear alkane 2 contained in each block are aligned with the molecular chains of the linear alkane 2 contained in the adjacent block. That is, in the film 3, the linear alkanes 2 arranged in parallel are periodically arranged in the molecular chain direction, that is, in the one-dimensional direction.

If the above-mentioned aryl compound as a chemical modification compound is reacted with the carbon material 1 shown in fig. 1 (c), the thin film 3 functions as a mask. Then, as shown in fig. 1 (d), the aryl radicals derived from the aryl compound are added to the surface of the carbon material 1 at the portions of the grooves between the blocks so as to sandwich the blocks composed of the linear alkane 2. By this reaction, the surface-modified carbon material 5 in which the chemical modification group 4 induced by the chemical modification compound is added to the surface of the carbon material 1 can be obtained.

As can be recognized from fig. 1 (d), in the method of manufacturing a surface-modified carbon material, the addition positions of the plurality of chemical modification groups 4 can be controlled by the thin film 3 used as a mask. The chemical modification group 4 is added so as to sandwich the linear alkane 2 constituting the thin film 3. Thus, the chemical modification groups 4 are linearly formed in 2 or 3 or more columns with a gap corresponding to the molecular length of the linear alkane 2, and are added to the carbon material 1. That is, the addition position of the chemical modification group 4 has periodicity in the molecular chain direction of the thin film 3 serving as a mask, i.e., in one-dimensional direction.

Thus, the addition sites of numerous chemical modifying groups have a defined periodicity on the surface. Thus, in the fourier transform image of the scanning probe microscope image of the surface-modified carbon material 5 surface, one-dimensional periodicity corresponding to the addition positions of the plurality of chemical modification groups 4 was observed. Fig. 1 (e) shows a photograph showing the surface of the surface-modified carbon material according to the present invention. The dimensions of the field of view are 200nm in the X direction and 200nm in the Y direction.

As described above, in the method for producing a surface-modified carbon material, the periodicity corresponding to the molecular length of the linear alkane or alkane derivative used can be obtained. That is, longer periodicity can be obtained if an alkane or alkane derivative having a longer molecular length is used, and shorter periodicity can be obtained if an alkane or alkane derivative having a shorter molecular length is used.

For example, when n-triacontane having a carbon number of 30 is used, a periodicity of about 3.5 to 4.5nm is obtained, when n-tetradecane having a carbon number of 40 is used, a periodicity of about 5.0 to 6.0nm is obtained, and when n-fifty alkane having a carbon number of 50 is used, a periodicity of about 6.5 to 7.5nm is obtained (see FIG. 1 (a)).

In the method for producing a surface-modified carbon material, the amount of the chemical modification group added to graphene or the like can be adjusted by increasing or decreasing the amount of the chemical modification compound that reacts with graphene or the like. The surface of graphene or the like, which is a carbon material, is a plane, which is preferable in that high-periodicity modification easily occurs. The surface may be periodically modified even if the surface has irregularities. However, if the chemical modification compound is reacted with a surface having irregularities, the chemical modification compound reacts with a portion having large irregularities. Then, if the surface irregularities are excessively large, periodic modification is difficult to occur.

Fig. 2 (a), (b) and (c) are schematic diagrams of surface-modified carbon materials. Fig. 2 (a) shows a surface-modified carbon material 15a obtained by not using a thin film such as alkane as a mask, which is a surface-modified carbon material according to the prior art. It can be seen that the chemical modification groups 14 are irregularly added to the surface of the carbon material.

Fig. 2 (b) and 2 (c) show a surface-modified carbon material produced by using a thin film such as an alkane as a mask. These surface-modified carbon materials shown in fig. 2 (a), (b) and (c) each show a surface-modified carbon material produced by reacting TBD with graphene or graphite.

The surface-modified carbon material 15a shown in fig. 2 (a) has many chemical modification groups 14, but the addition positions of the chemical modification groups 14 are not controlled, and the addition positions in the in-plane direction are irregular, and have no periodicity. Therefore, no periodicity corresponding to the addition position of the chemical modification group 14 was observed in the fourier transform image of the scanning tunneling microscope image of the surface-modified carbon material 15a.

The surface-modified carbon material 15b shown in fig. 2 (b) and the surface-modified carbon material 15c shown in fig. 2 (c) are optimal surface-modified carbon materials produced by using the thin film 13 formed by arranging the linear alkanes 12 in parallel as a mask, and are linearly added along the grooves between the blocks of the linear alkanes 12 constituting the thin film 13 so that the linear alkanes 12 are sandwiched by a plurality of chemical modification groups 14.

That is, a plurality of chemical modification groups 14 are added at intervals corresponding to the molecular length of the linear alkane molecule 12. As a result, the addition positions of the plurality of chemical modification groups 14 are controlled. Only one block (membrane unit) is shown in fig. 2 (b) and (c). Fig. 1 (c) and (d) schematically show a film 13 having three pieces arranged on the surface of a carbon material.

Thus, periodicity corresponding to the addition position of the chemical modification group 14 was observed in the fourier transform image of the scanning tunneling microscope image of the surface-modified carbon materials 15b and 15 c. The period is a length corresponding to the length of the linear alkane 12 molecule. The surface-modified carbon material 15c has chemical modification groups 14 added thereto at a higher density than the surface-modified carbon material 15 b. The dashed lines marked in fig. 2 (b) and (c) show the arrangement of the linear alkane 12 constituting the film 13.

In the present invention, the arrangement of the chemical modification groups is not limited to the case where the chemical modification groups can be recognized as being arranged in a substantially straight line on the STM observation image. The present invention includes, for example, cases where the positions where the chemical modification groups are added are arranged in a band-like region having a width of about 2 to 3nm, preferably about 1 to 2nm, in a predetermined direction showing periodicity. Where chemical modifying groups are added, it is of course considered to be encompassed by the present invention if the macroscopic display of the periodic arrangement is present. The band-shaped region corresponding to the "mask" gap may be an unstable region, but the shape on the surface may be linear or curved as long as the shape does not deviate from the periodic condition.

In addition, the interval between the chemical modification groups added in the direction perpendicular to the predetermined direction showing periodicity, that is, the direction perpendicular to the long axis direction of the alkane is larger than about 1nm, and no periodicity is shown. The one-dimensional periodicity is maximally extended to the entirety of thin film particles such as alkanes. In addition, the typical particle area ratio is 1. Mu.m ² Larger left and right.

The surface-modified carbon material of fig. 1 (d), 2 (b) and 2 (c) shows a state in which a thin film such as an alkane used as a mask is attached to the surface of the carbon material. However, the film may be removed from the surface of the surface-modified carbon material. If the film is used as a precursor, which does not affect the element characteristics, the film may be left as a protective layer for protecting the surface of the carbon material without being removed.

As a specific example of the method for producing the surface-modified carbon material, a method using an electrochemical cell (hereinafter referred to as electrochemical method) is given. A method of using the electrochemical cell will be described with reference to fig. 3 (a) to (g). The surface-modified carbon material is produced by electrochemically reacting a chemical modification compound with a carbon material using the electrochemical cell. As the aqueous electrolyte solution, an aqueous solution containing a chemical modification compound is used, and a liquid medium containing a compound exhibiting periodic self-assembly properties is disposed between the working electrode and the aqueous electrolyte solution. In this case, the aqueous electrolyte solution and the liquid medium are non-miscible with each other.

First, fig. 3 (a) is an external photograph of an example of an electrochemical cell used in the method for producing a surface-modified carbon material. The host material of the electrochemical cell is, for example, PTFE. Fig. 3 (b) and (c) are schematic cross-sectional views of electrochemical cells. Fig. 3 (d) to 3 (g) are references from the above non-patent document 11, and fig. 3 (d) shows voltage-current characteristic curves in the case where NBD and TBD are used for surface modification of a carbon material and a CV method is applied. FIGS. 3 (e) and (f) are graphs showing comparative Raman spectrum results after surface modification with NBD and TBD. These methods are utilized in the present invention directly or indirectly as an essential element in terms of manufacturing.

Fig. 3 (g) is a graph showing voltage-current characteristics after reduction treatment by cyclic voltammetry (CV method) for chemical modification using TBD, and a graph showing raman spectra before and after treatment by CV method.

The graph (1) of fig. 3 (g) shows the voltage/current characteristics at the time of 3 scans, and the curves intersecting the vertical axis show the cases of the 1 st, 2 nd and 3 rd scans in the order from the bottom. The electrochemical reaction, i.e., reduction of the aryl diazonium salt, in scan 1 was almost complete, as the current decreased with increasing number of scans, indicating that the reaction tended to terminate. Subgraph (2) (3) shows raman spectra before and after modification.

The electrochemical cell 20 shown in fig. 3 (b) and (c) includes a working electrode 21, a counter electrode 22, and a reference electrode 23. The working electrode 21 is graphene or graphite. In this method for producing a surface-modified carbon material, a chemical modification compound is electrochemically reacted with graphene or graphite as a working electrode to produce a surface-modified carbon material. The counter electrode 22 is, for example, a platinum electrode, and the reference electrode 23 is, for example, a silver/silver chloride electrode. As an example, in FIG. 3 (c), the cylindrical portion of the device is upper H in the height direction ₁ 35mm, lower part H ₂ Is 3mm.And +.>For the inner diameter of the internal reaction tank, e.g. upper +.>20.4mm, lower +.>7mm.

In the electrochemical cell 20, a liquid medium 24 containing a compound exhibiting periodic self-assembly properties is disposed on the working electrode 21, and an aqueous electrolyte solution 25 is disposed on the liquid medium 24. The liquid medium 24 has a property of being separable from the aqueous electrolyte solution 25, and is not mixed with the aqueous electrolyte solution 25.

The size of graphite as a carbon material is, for example, 12mm in the longitudinal direction and 12mm in the transverse direction and 2mm in the thickness. There is no lower limit on the thickness, and the thickness can be handled even if it is thin. The upper limit of the thickness may also be set to several cm. In the case of graphene, for example, the length is 10mm×the width is 10mm×the thickness is 1mm. In this example, a single-layer graphene of a commercially available product of a copper film (thickness 35 μm) supported on a plastic substrate was used. Alternatively, the electrochemical treatment may be performed with the graphene nanoribbon having terminals formed in advance on the silicon substrate.

The method for producing a surface-modified carbon material according to the present invention is characterized in that a liquid medium such as an alkane containing a compound that exhibits periodic self-assembly properties is disposed between a working electrode and an aqueous electrolyte solution. In the conventional method for producing a surface-modified carbon material using an electrochemical cell, the above-described liquid medium is not disposed between graphene or graphite as a working electrode and an aqueous electrolyte solution.

For the Cyclic Voltammetry (CV) used in the present invention, an arbitrary voltage generating device (function generator) and a precision voltage source (voltage stabilizer), an electrochemical cell, an X-Y recorder, a waveform observing device (oscilloscope) and the like may be prepared. The voltammogram can be recorded on an X-Y recorder by setting the scanning speed to 0.01V-0.50V/sec. The electrochemical action on the sample is generated as a target on the electrode of the working electrode. The potential is scanned in the negative direction in the reaction tank to generate a reduction wave. Cyclic voltammograms (cyclic voltammogram) with applied potential as the horizontal axis and response current values as the vertical axis can be recorded for each sample. Examples of the cyclic voltammetry device include a pgstate 101 voltage stabilizer from Autolab, and an ALS electrochemical analysis series (600 series) from ALS/CH instruments.

In the present invention, the aqueous electrolyte solution 25 in the electrochemical cell is an aqueous solution containing a chemical modification compound. The aqueous electrolyte solution 25 contains an electrolyte such as sodium nitrite and hydrochloric acid in addition to the chemical modification compound.

In the electrochemical cell 20, when the electrode potential is scanned, the chemical modification compound contained in the aqueous electrolyte solution 25 reacts with a carbon material such as graphene or graphite that is the working electrode 21, and a chemical modification group is added to the surface of graphene or the like that is the working electrode 21. In the case where the chemical modification compound is a compound represented by the above formula (3), the chemical modification compound is reduced to generate an aryl radical, and the aryl radical is added to the surface of graphene or the like that is the working electrode 21. Using this electrochemical reaction mechanism, chemical modifying groups are controllably added to the surface of the carbon material.

An important element for carrying out the present invention is to dissolve organic compound molecules as a mask in a nonpolar organic solvent having a small dielectric constant, dispose the organic compound molecules on the surface of a carbon material such as graphite, and dispose an aqueous electrolyte solution containing an aryl diazonium salt thereon.

By constructing the new method which has not been known in the past, formation of a thin film as a mask (organic compound molecule) from an organic solvent is successfully promoted on the surface of a carbon material in a controlled manner.

Then, when chemical modification groups are added to the surface of the carbon material, it is not completely understood how the periodicity is exhibited. As one conceivable mechanism of action, it is considered that dynamic fluctuation is successfully caused to the mask as the chemical reaction proceeds. According to the constitution of the present invention, it is possible to reliably form a chemical modification group (adduct) on the surface of a carbon material in a manner exhibiting periodicity. Therefore, successful focusing on the constitution using a combination of a film and an organic solvent is of great importance.

FIG. 3 (d) shows a comparison of the case where NBD is used as the chemical modification group and the case where TBD is used when the reduction treatment is performed by CV method. In either case, the 1 st scan was performed from the lower side of the vertical axis of the graph. When the chemical modification group is TBD, the voltage-current characteristic can be recognized as being gradually changed after CV method treatment.

Next, in order to compare the case where NBD is used as the chemical modification group with the case where TBD is used, fig. 3 (e) shows an example of raman spectrum in the case where NBD is used as the chemical modification group, and fig. 3 (f) shows an example of raman spectrum in the case where TBD is used as the chemical modification group. It can be seen that in the case of NBD of FIG. 3 (e), id/Ig did not change significantly.

In contrast, it was confirmed that when TBD was used in FIG. 3 (e), id/Ig was greatly changed according to the TBD content. At a TBD level of 5mM, the Raman spectrum has an Id/Ig of about 0.10.

In the present invention, cyclic voltammetry (CV method) was used as the electrochemical method in the following examples. However, the present invention is not limited to the CV method, and basically can be applied to a method that can cause a reduction reaction, such as differential pulse voltammetry, chronoamperometry, and chronocoulometry.

In forming the thin film used in the production method of the present invention, the compound exhibiting periodic self-assembly property contained in the liquid medium 24 is periodically self-assembled, and is attached to the surface of graphene or the like serving as the working electrode 21 as a thin film having a periodic structure (i.e., one-dimensional periodic or two-dimensional periodic). The thin film functions as a mask in the reaction of the chemical modification compound with the surface of graphene or the like that is the working electrode 21, and as described above, the chemical modification group has a periodic addition to graphene or graphite that is the working electrode 21. The organic compound-carbon material composite 26 according to the present invention is present in the process.

The compound used in the present invention may be one which can be self-assembled periodically to form a thin film having a periodic structure, and the chemical modification compound may be bonded periodically to the surface of graphene or the like in accordance with the periodicity. There is no particular limitation as long as it is a compound exhibiting such properties. In the present invention, the above-mentioned compounds showing periodic self-assembly include compounds which maintain one-dimensional periodicity and compounds which maintain two-dimensional periodicity (see "A electrochemical treatment" of FIG. 4 (e) described in detail below)

Thus, if a compound which is assembled while maintaining one-dimensional periodicity is used as the above-described compound which exhibits periodic self-assembly properties, a surface-modified carbon material in which periodicity corresponding to the addition positions of a plurality of chemical modification groups can be observed in one-dimensional direction can be obtained. Furthermore, if a compound that is assembled while maintaining two-dimensional periodicity is used, a surface-modified carbon material in which periodicity corresponding to the addition positions of a plurality of chemical modification groups can be observed in two dimensions can be obtained.

Examples of the compound to be assembled while maintaining one-dimensional periodicity include linear alkane derivatives having 15 to 80 carbon atoms, preferably 16 to 60 carbon atoms, and linear alkane derivatives having 10 to 80 carbon atoms, preferably 12 to 60 carbon atoms.

In the present invention, if these linear alkanes or linear alkane derivatives are used, these organic compounds are self-assembled periodically, and are attached to the surface of a carbon material such as graphene, which is the working electrode 21, as a thin film having the one-dimensional periodic structure (for example, as a layered monomolecular film).

The honeycomb structure has a certain periodic arrangement along the main axis direction of carbon constituting a carbon material such as graphene. The whole surface is not covered, as long as the periodicity is displayed in a certain area. Thus, as the compound exhibiting periodic self-assembly properties, a linear alkane or a linear alkane derivative can be used. In this way, as described above, a periodic surface-modified carbon material corresponding to the addition positions of a plurality of chemical modification groups can be observed in one dimension in the fourier transform image of the scanning probe microscope image of the surface.

Examples of the compound to be assembled while maintaining two-dimensional periodicity include dehydrobenzo [12] rotarene derivatives.

If a dehydrobenzo [12] rotarene derivative is used, it periodically self-assembles into a hexagonal shape, and is attached to the surface of a carbon material such as graphene, which is the working electrode 21 of an electrochemical cell, as a thin film having a hexagonal continuous structure (i.e., a honeycomb structure). Thus, if a dehydrobenzo [12] rotaene derivative is used as the above-mentioned compound exhibiting periodic self-assembly properties, a periodic surface-modified carbon material in which addition positions corresponding to a plurality of chemical modification groups are observed in two dimensions in a fourier transform image of a scanning probe microscope image of the surface can be obtained.

The dehydrobenzo [12] rotaene derivative is represented by the following formula (4), for example.

[ chemical formula 10]

R＝C _n H _2n+1 Or OC (alpha) _n H _2n+1 …(4)

In the formula (4), n is an integer of 4 to 30.

Periodic self-assembly of dehydrobenzo [12] rotaene derivatives is illustrated by FIGS. 4 (a) - (d). FIG. 4 (a) is a diagram schematically showing a structure of a dehydrogenated benzo [12] rotaene derivative which can be an example of the basic skeleton 30.

The three benzene rings in the above formula (4) are bonded to form a triangle-shaped structure corresponding to the triangle in the central portion of fig. 4 (a). The alkyl chain or alkoxy group R bonded to each benzene ring is shown by 6 elongated rectangles extending from the triangular portion as branches. Then, as shown in FIG. 4 (b), 6 molecules of the dehydrobenzo [12] rotarene derivative contained in the liquid medium 24 are assembled so that alkyl chains or alkoxy groups are juxtaposed with each other to form a hexagonal periodic structure 33U.

Further, as shown in fig. 4 (c), many molecules are assembled in such a manner as to form a continuous hexagonal shape structure. As a result, the thin film 43 is formed on the surface of the carbon material 41 as if it were assembled and formed in the honeycomb structure assembly 33U. In this way, the thin film 43 is attached to the surface of the carbon material 41 such as graphene that operates as a working electrode. If the chemical modification compound is reacted with the carbon material 41 in this state, the thin film 43 functions as a mask, and the chemical modification compound reacts with the surface of the carbon material 41 at the void portions (voids) of the assembly 33U having a hexagonal shape of the thin film 43.

Then, as shown in fig. 4 (d), a surface-modified carbon material 45 can be obtained in which the surface-modifying group 44 is added in correspondence to the periodicity of the continuous hexagonal structure (assembly 33U) possessed by the thin film, which periodicity remains in the two-dimensional direction. Fig. 4 (d) shows a case where each of seven hexagonal voids is added with a chemical modifier 44. The longer the six alkyl chains or alkoxy groups of the dehydrobenzo [12] rotarene derivative are, the larger hexagonal voids are formed in the film, and the larger chemical modification compound can react with the carbon material. However, if the hexagonal shape is too large, the function of the thin film as a mask is impaired, and the addition position of the chemical modification group cannot be sufficiently controlled, so that the periodicity of the addition position of many chemical modification groups is lowered.

On the other hand, the shorter the six alkyl chains or alkoxy groups of the dehydrobenzo [12] rotarene derivative are, the smaller the hexagonal voids are formed in the film, and the more easily the addition positions of a plurality of chemical modification groups are controlled. Thus, the addition position of the chemical modification group in the entire surface periodically rises. However, although a surface-modified carbon material having a short period is easily obtained, it is difficult to obtain a surface-modified carbon material having a long period. If the hexagonal voids are too small, the large chemical modifier compound cannot react with the carbon material, and only the small chemical modifier compound can react with the carbon material.

For the above reasons, the length of the six alkyl chains or alkoxy groups possessed by the dehydrobenzo [12] rotarene derivative is appropriately determined in accordance with the desired periodicity and the chemical modification group to be added. In the formula (4), n is preferably an integer of 5 to 30, more preferably an integer of 6 to 14. For example, in the case of using TBD as the chemical modification compound, if a dehydrobenzo [12] rotaene derivative in which n is an integer of 6 to 10, preferably an integer of 6 to 8 in the formula (4) is used, a surface-modified carbon material having high periodicity can be obtained.

The six alkyl chains or alkoxy groups of the dehydrobenzo [12] rotaene derivative need not be the same length, and it is not relevant that the respective lengths are different as long as the above properties can be obtained. R in formula (4) may be the same or different.

Further, as the dehydrobenzo [12] rotaene derivative, there is no relation to a compound wherein R is a triple bond and a double bond, and a group containing a branching chain and a functional group, as shown in the formula (4).

Next, fig. 4 (e) is an explanatory diagram showing the flow and relationship of the steps of [ a ] electrochemical treatment, [ B ] self-assembled monolayer, [ C ] nanopatterning according to covalent bond formation, and [ D ] surface modification according to an adduct in the production method according to the present invention. The electrochemical cell 20 is internally provided with a working electrode 21, a liquid medium 24, an aqueous electrolyte solution 25, and an organic compound-carbon material composite 26. The production method of the present invention includes, as an essential condition, step 1 of forming a self-assembled monolayer, and step 2 of chemically modifying the surface of a carbon material using the self-assembled monolayer as a mask.

Further, the embodiment of the present invention will be described with respect to the use of an organic compound capable of being assembled while maintaining a two-dimensional periodic structure. As described above, as long as the periodic addition of the chemical modification group is possible, in addition to the compound forming the hexagonal periodic structure such as the dehydrobenzo [12] rotarene derivative, a compound which can form a thin film having a symmetrical structure and continuing on a plane such as a triangle, a quadrangle, an octagon, or a star-shaped polygonal shape (including a regular star-shaped polygonal shape such as a cage structure) may be used.

That is, the compound may be a compound in which the compound is continuously assembled in the planar direction on a single unit basis to form a thin film having a periodic structure as a whole. Basically, it is preferable to use a compound which is continuously assembled on the surface of a carbon material and exhibits a periodic, symmetrical ring structure.

That is, the assembly of the organic compound may be one in which the central structure portion and the peripheral structure portion are connected by intermolecular interaction, and the periodic structure may be formed as a whole. In addition to the above dehydrobenzo [12] rotaene derivative, for example, 1,3, 5-tris (4-carboxyphenyl) benzene (H3 BTB) is preferably assembled in a honeycomb form, and is also preferably provided in a form having a two-dimensional periodic structure.

Fig. 5 (a) shows an example of the basic form of a carbon material 200 covered with a two-dimensional periodic mask used in the production of a surface-modified carbon material having two-dimensional periodicity according to the present invention. The thin film 203 is formed on the surface of the carbon material 6-membered ring planar arrangement 202. The film 203 is composed of an assembly in which a plurality of basic skeletons 205a and branches 205b composed of an organic compound are connected to each other so as to cover the surface. The plurality of assemblies are arranged in a manner having a periodic structure on the face. The size of the void may be approximated by a polygon 200S inscribed therein. For example, the size of the hollow in the assembly is preferably set to 2.6 to 12.3nm ² Left and right. In this case, the shape of the hollow hole is preferably a hexagon, more preferably a regular hexagon.

Alternatively, the size of the hollow in the assembly may be approximated by the length of the hollow in the X direction and the Y direction (cross 200 XY) with reference to a predetermined direction (for example, the main axis direction of the carbon material). In order to maintain the ordered arrangement of the adducts and to arrange them at a high density when the surface of the carbon material is modified, it is preferable that the length of the pores in the assembly in the X direction be 1.6 to 3.5nm and the length in the Y direction be 1.6 to 3.5nm, for example.

The size of the hollow structure of the two-dimensional periodic structure formed by the assembly of the single units is set to 5nm or less. Since the pores become smaller by 5nm or less, the adduct per unit area on the surface of the carbon material becomes high in density. More preferably 3nm or less (see FIG. 5 (b)). For example, when the form of the void is a polygonal shape or a star-shaped polygonal shape, the dimension of the void corresponds to the case where the longest diagonal line in the inscribed shape is 5nm or less.

In the present invention, a thin film having a two-dimensional periodic structure with such a void size is used as a mask, and the adduct is modified on the surface of the carbon material. In this case, it is considered that the amount of the adduct which can enter the hole is changed with respect to the size defined by the hole. In the case of small voids, it is considered that DBA-OC4 is 1 to 2 and DBA-OC10 is about 1 to 4. That is, depending on the relative relationship between the pore size and the adduct (chemical modifying group), the proportion of the adduct added to the partition corresponding to a predetermined unit area in the surface area may vary.

In the present invention, a surface-modified carbon material comprising a plurality of chemical modification groups added to a surface of at least a part of a carbon material selected from the group consisting of graphene, graphite, glassy carbon film and membranous thermally decomposed carbon is preferable, wherein the surface-modified carbon material has a two-dimensional periodicity of a plurality of addition positions corresponding to the chemical modification groups in a Fourier transform image of a scanning probe microscope image of the surface, and a predetermined unit area of the surface is 5 to 15nm ² The proportion of 1 or more adducts (spots) is present, i.e., the proportion of adducts in the planar direction is 70% or more. The above ratio is more preferably 75% or more, and still more preferably 90% or more.

In the STM observation image, when several tens of adducts (surface chemical modification groups) are present in the field of view, the entire area of the field of view is divided into predetermined unit areas, and it is determined whether or not 1 or more adducts (spots) are present in each of the unit areas, whereby the proportion of the adducts in the plane direction can be obtained. For example, a predetermined unit area of 5 to 10nm ² 、5～15nm ² In the case of the left and right, the total number of the adducts may be used. Thus, when the adduct is formed almost uniformly on the surface area of the object, the total number of adducts (number per unit area) in the STM observation image can be almost replaced.

An example of a method for evaluating the in-plane density, the modification ratio, and the like of an adduct in the present invention will be described below. Specifically, a method of performing approximate analysis on a plurality of flare points in an STM observation image using image analysis software is provided.

Regarding the graphite in which the chemical modification group was added to the surface of the carbon material so as to exhibit two-dimensional periodicity using the DBA-OC6 as a mask, one STM observation image (200 nm. Times.200 nm,40000 nm) was obtained using image analysis software ² ) The number of spots present in the field of view is analyzed. The flare herein is considered to correspond to the position of numerous adducts (aryl groups) added to the surface of the carbon material.

Regarding the STM observation Image, a particle Kong Jiexi model of SPIP Image analysis software (manufactured by Image technology corporation) was applied, and the presence of flare was detected with a height of 150pm or more as a standard value assuming that the graphene surface was a basal plane. As a result, about 3500 spots were detected in the target area.

Each spot has a unit area of 40000nm ² 3500 = 11.4nm ² . In addition, since the lattice unit area of the honeycomb structure of DBA-OC6 is 8.87nm ² Therefore, if it is taken as a prescribed cell area, assuming that the two-dimensional periodicity (honeycomb arrangement in the plane direction) is entirely present, the ratio thereof is 8.87nm ² /11.4nm ² ＝78％。

In order to adjust the ratio to 90% or more, the chemical reaction by the CV method can be repeated so that the chemical modification groups are efficiently added in the plane while adjusting the pore size of the assembly of the thin film and the space size of the adduct.

Thus, the surface of the carbon material is chemically modified by electrochemical treatment using an electrochemical cell, a self-assembled monolayer is formed on the surface, and the chemically modified groups are covalently bonded, thereby applying nanopatterning. Fig. 4 (a) to (e) show changes in the respective steps when the surface of the carbon material is chemically modified with the adduct.

In the above assembly formed by assembling DBA, 2 alkyl groups of 2 molecules of DBA adjacent to each other are juxtaposed alternately. The relative configuration of 2-molecule DBAOC6 on the surface is shown in fig. 29. The left panel of fig. 29 shows the-type, and the right panel shows the + type. Depending on the relative arrangement of the 2 molecules, the assembly may have 2 structures having chiral relationships with each other, i.e., a right-hand (CW) structure and a left-hand (CCW) structure. The CCW structure and the CW structure are each constituted by 2 intermolecular interactions different from each other. The CW structure is composed of only 6 molecules with type-interaction, and the CCW structure is composed of only 6 molecules with type-interaction. It is also possible to consider a deformed hexagonal structure in which a mixture of the-type and the + type exists in one hexagonal structure, but it is a disadvantageous structure in view of surface molecular density and intermolecular interaction. FIG. 26 (a) shows the CW structure in an assembly formed by DBAOC6 hexamolecular assembly, and FIG. 26 (b) shows the CCW structure. Arrows shown inside the assembly of fig. 26 (a) and 26 (b) show the rotational directions corresponding to CW (close wise) and CCW (Counterclockwise). The CW structures and the CCW structures each form different regions that appear on the surface with equal probability. Thus, the areas of the CW and CCW structures are equal in each case in the entire surface.

The vector of lattice cells of the honeycomb structure formed by DBA assembly is inclined in the counterclockwise direction in the CCW structure and in the clockwise direction in the CW structure with respect to the graphite main axis (main symmetric axes) nearest thereto. That is, the relative angles for the graphite substrate in the CCW structure and the CW structure are different.

Fig. 27 (a) shows an STM observation image in the vicinity of the region boundary of the honeycomb structure (template) formed by DBAOC6, and fig. 27 (b) shows a fourier transform image. The white lines shown in the STM observation image of fig. 27 (a) correspond to region boundaries. The white line is a line marked by a boundary at which particles of the bright point arrangement on the image are switched with the naked eye. The white line forms a CW structure in the left region and a CCW structure in the left region. In the fourier transform image of fig. 27 (b), 2 periods of six rotational symmetries are observed. One is a period represented by a spot caused by a honeycomb structure of a CW structure surrounded by a dotted circle, and the other is a period represented by a spot caused by a honeycomb structure of a CCW structure surrounded by a solid circle. The angular difference between the period of the CW structure and the CCW structure is about 13 °.

Further, fig. 28 (a) shows an STM observation image of a modified graphite surface obtained by chemically modifying graphite using DBAOC6 as a template aryl group, and fig. 28 (b) shows a fourier transform image. With white lines shown in the STM observation image of fig. 28 (a) as boundaries, 2 periods of six rotational symmetries are observed in the fourier transform image of fig. 28 (b). The white line is a line marked by a boundary at which particles of the bright point arrangement on the image are switched with the naked eye. One of the periods is a period represented by a spot surrounded by a circle of a broken line, and the other period is a period represented by a spot surrounded by a circle of a solid line. The angular difference between the two periods is about 14 °.

The angular difference of 14 ° between the two periods observed in this surface-modified graphite is similar to the angular difference of 13 ° between the periods of the CW and CCW structures in the DBAOC6 template described above. If the standard deviation is calculated from the average of several experimental values, it is at most 2 °, it can be evaluated that there is no difference between the two values.

It is strongly suggested that the 2 cycles observed on the modified graphite surface are caused by the chiral structure formed by DBAOC6 (i.e., CW structure as well as CCW structure). That is, the chiral honeycomb information of DBAOC6 propagates to the site of the aryl group added to the graphite. This corresponds to the introduction of defects (sp ³ Carbon).

Further, based on the signal positional relationship of the fourier transform image, it is considered that chemical modification reflecting the period of the CCW structure of the template occurs in the upper region of the white line shown in the STM observation image of fig. 28 (a), and chemical modification reflecting the period of the CW structure occurs in the lower region.

As described above, in the surface modification of a carbon material using DBA as a template, the periodicity of the chemical modification group can be controlled based on the chirality possessed by an assembly of DBA or the like.

Comparative example

Next, a case where a liquid medium is not applied in the electrochemical treatment step will be described in comparison. The same procedure as described above was performed under the condition that the surface of a carbon material such as graphene, which is a working electrode, was covered with a monomolecular film such as dried alkane prepared in advance without disposing the above-described liquid medium between the working electrode and the aqueous electrolyte solution. Then, the addition reaction of the chemical modification compound to graphene and graphite is suppressed, but the periodicity of the addition positions of many chemical modification groups is not obtained.

[ Effect ]

In contrast, if the above-described liquid medium is disposed between the working electrode and the aqueous electrolyte solution and the above-described operation is performed, the periodicity of the addition positions of the plurality of chemical modification groups can be obtained. This is considered to be because, in the method of covering a monolayer of an alkane or the like prepared in advance, alkane molecules in a thin film of the covered alkane or the like do not dynamically fluctuate, whereas in the method of disposing the liquid medium between a working electrode and an aqueous electrolyte solution, alkane molecules in a thin film of an alkane or the like attached to a surface of graphene or the like can dynamically fluctuate.

In the method of disposing the above-mentioned liquid medium between the working electrode and the aqueous electrolyte solution, it is considered that the film of alkane or the like having a one-dimensional periodic structure can be obtained because the following effects are exhibited.

In the present invention, it is considered that a monomolecular film such as alkane formed by disposing a liquid medium between a working electrode and an aqueous electrolyte solution is in a dynamic state, and a fluctuation occurs, and a gap having a low limit barrier is generated in the monomolecular film.

The liquid medium 24 can be obtained by dissolving the alkane or the like in a nonpolar organic solvent or a low-polarity organic solvent, for example. The alkane and the like contained in the liquid medium 24 are as described above. The nonpolar organic solvent or the low-polarity organic solvent is not particularly limited as long as it can dissolve the alkane or the like, and the liquid medium 24 obtained by dissolving the alkane or the like and the aqueous electrolyte solution 25 are mutually non-miscible. For example, 1-octanoic acid, 1-phenyloctane, tetradecane, 1-octanol, 1,2, 4-trichlorobenzene and the like can be preferably used.

The concentration of the alkane or the like in the liquid medium 24 is preferably 1. Mu. Mol/L or more, more preferably 1 mmol/L or more. If the concentration of the alkane or the like is within the above range, the thin film having a one-dimensional periodic structure is easily formed, and it is preferable to manufacture a surface-modified carbon material having periodicity. The upper limit of the concentration of the alkane or the like is not particularly limited, but is, for example, 1 mol/L.

In the case of treatment with the electrochemical cell used in the present invention (see fig. 3 (a) to (c)), the amount of the liquid medium 24 is not particularly limited as long as the thin film having the one-dimensional periodic structure can be formed, and the size of the electrochemical cell 20 can be appropriately determined.

The chemical modification compound contained in the aqueous electrolyte solution 24 is as described above. The concentration of the chemical modification compound in the aqueous electrolyte solution 24 is preferably 0.1 to 20 mmol/L, more preferably 0.2 to 10 mmol/L. If the concentration of the chemical modification compound is within the above range, the chemical modification compound reacts well with the carbon material such as graphene, which is the working electrode 21, and a sufficient amount of chemical modification groups for exhibiting periodicity is easily added to the surface of the carbon material such as graphene.

Further, the concentration is more preferably 1 to 5 mmol/L. If the concentration of the chemical modification compound is in the above range, the chemical modification compound reacts well with the surface of the carbon material such as graphene, which is the working electrode 21, and a sufficient amount of chemical modification groups exhibiting periodicity at the same time are easily added to the surface of the graphene.

An example of the production method of the present invention is shown in fig. 5 (c), which shows a flowchart (step S _START ～S _END ). First, a single compound that can be assembled by interaction and form a monomolecular film is selected. Preparing an organic compound which can have a basic structural unit and a periodic structure in the whole structure of the assembly (step S) ₁ ). Then, a thin film of the organic compound is formed on the surface of the carbon material (step S ₂ ). The thin film is formed and arranged so as to cover at least a part of the surface of the carbon material.

The thin film is disposed on the surface of the carbon material and then functions as a mask in the subsequent steps. First, in order to form a one-dimensional periodic structure, the arrangement structure of the organic compounds constituting the thin film fluctuates, and a gap having a low limit barrier is formed at a part of the thin film. Therefore, it is considered that a one-dimensional periodic structure derived from the periodic structure is formed in the planar direction of the carbon material. In order to form a two-dimensional periodic structure, it is considered that the film contains pores having a low limit barrier in advance, and thus the carbon material exhibits a two-dimensional periodicity derived from the two-dimensional periodic structure in the plane direction.

Next, a chemical modification compound is added from the surface side of the carbon material using the thin film as a mask (step S) ₃ ). In this case, the chemical modification compound may be disposed so as to correspond to the gaps and the voids over the entire surface of the surface. Then, the chemical modification compound is reacted with the carbon material, and a chemical modification group is added to the surface and fixed. As a result, the adduct in the whole surface is arranged to have a predetermined periodic structure (step S ₄ )。

Finally, the thin film used as a mask is removed by a solvent or the like (step S ₅ ). Thus, the surface of the carbon material can be chemically modified with an adduct having a predetermined periodic structure (step S) _END )。

The gist of the present invention will be described again with reference to fig. 4 (e). A solution bilayer forms at the bottom of the electrochemical cell, temporarily forming an organic compound-carbon material complex 26. Then, a thin film of an organic compound such as alkane is formed on the surface of the carbon material. In the film, blocks (membrane units) are formed in units of the molecular length of alkane, and grooves are formed between the blocks. The difference in the lengths of the corresponding alkane molecules varies in length (i.e., spacing) between the adjacently present grooves. Further, no organic compound is present in the portion of the groove, and the surface of the carbon material is exposed. Then, chemical modification of the adduct by covalent bond formation to the carbon material occurs, resulting in nanopatterning of the carbon material surface.

Finally, after the film is removed from the entire surface of the carbon material, numerous adducts (chemical modification groups) having a predetermined order in the planar direction are formed on the surface of the carbon material. Fig. 5 (b) shows the relative sizes of the assemblies (single units) in an STM observation image of the surface of a carbon material.

In the method for producing a surface-modified carbon material according to the present invention, as described above, a thin film is formed on a carbon material that is a working electrode by a compound exhibiting periodic self-assembly properties, and a nonpolar organic solvent or a low-polarity organic solvent is disposed on the thin film. That is, an organic compound-carbon material composite is formed which has a carbon material such as graphene, a thin film formed by a compound exhibiting periodic self-assembly properties, and a nonpolar organic solvent or a low-polarity organic solvent present on the thin film.

In the organic compound-carbon material composite, the carbon material is a site where the carbon material is subjected to chemical modification groups later to be added as a surface-modified carbon material, and the thin film is a site functioning as a mask as described above. The nonpolar organic solvent or the low polar organic solvent is a site that may contain a chemical modification compound that provides a chemical modification group to the carbon material. That is, the organic compound-carbon material composite can be considered as a material used for the production of the surface-modified carbon material.

Next, other configurations of the surface-modified carbon material according to the present invention, i.e., a uniform pitch type electronic device 90F in fig. 5 (d), and a configuration of the surface-modified carbon material according to the present invention, i.e., a non-uniform pitch type electronic device 90P in fig. 5 (e), will be described with reference to the drawings. These are methods capable of producing a surface-modified carbon material having a desired structure without using an addition step using the above mask. In the electrochemical method, if a template in which a plurality of molecules having different molecular lengths are mixed is used, it is considered that a surface-chemically-modified carbon material having a one-dimensional periodicity with different pitches can be formed. For example, when molecules having a molecular length of 3nm and 5nm are mixed, it is considered that a material having a pitch length of 3,5,3,5, 3,5 (unit: nm), or the like can be obtained.

First, the entire surface of the carbon material is subjected to random chemical modification in advance, and then, the chemical modification groups are gradually removed with positional accuracy of about several nm or less using an STM probe, and a part of the surface of the carbon material is exposed to prepare a void region 92. In addition, electrodes 95, 96 are formed in advance at both ends of the channel. Thus, numerous chemical modification groups 94 added to the 6-membered ring carbon positions remain in the desired positions on the surface of the carbon material. Instead of the void space 92 being processed into a rectangular shape, it may be processed into an arbitrary shape such as a circular shape, an elliptical shape, an oblong shape, or a shape including a part of a curve in addition to a straight line portion. Alternatively, the comb teeth of the electrodes from both sides may be formed so as to be engaged with each other with respect to the channel.

The regions from which the chemical modification groups are removed are a plurality of void regions 92 having a rectangular shape. This is because, as described above, by the operation of the STM probe, the chemically modifying group at the target site can be removed. As a result of this removal operation, the spacing of the void regions 92 in the channel direction can be made uniform in pitch dimension (W _F ) Is different from the case of the other and different pitch sizes (W _P ) Is prepared by any distinction in the case of (a). Furthermore, the periodic structure can be freely formed. In this way, the addition position of the chemical modification group can be designed and produced with high accuracy, and thus it is considered that the band gap size of the carbon material can be controlled.

This configuration example is a method using a nano-shaving method, and requires a considerable time for directly preparing a channel having a large area. However, if the channel size is about 10 to 30nm×20 to 60nm, a surface-modified carbon material exhibiting a one-dimensional periodicity of a desired pitch can be easily produced without any problem. Further, the arrangement of chemical modification groups having a two-dimensional periodicity is theoretically possible, but it is considered that the working time will be increased as compared with the case of a one-dimensional periodicity. Further, after chemical modification having a periodic structure is applied using a mask, a method of performing fine 2 times of processing by applying a nano-shaving method may be also applied.

In addition, in the present invention, even if the nano-shaving method is used, surface processing with the size of a very elongated single-row adduct (for example, one aryl group) as a width unit is considered to be difficult. Since the nanoshaving method physically scrapes off the adduct (chemical modification group) using a fine probe of STM and AFM (the size of the vertex portion is not necessarily atomic), performing surface processing in such a manner that only fine single columns are reliably retained requires an extremely high degree of experimental technique, and it is generally difficult to stably and reliably prepare.

Next, a method for capturing a periodic structure in the present invention will be described. Fig. 6 (a) is a schematic view showing a case where chemical modification groups have one-dimensional periodicity arranged on the surface of a carbon material. This corresponds to the case where the STM observation image is observed in the predetermined field size 60. Whether or not the chemical modification groups have one-dimensional periodicity is determined by assuming a one-dimensional arrangement 61 in which one unit size is rectangular, capturing the one-dimensional arrangement as one size, and determining whether or not the arrangement state of the plurality of adducts 64 can correspond to the one-dimensional arrangement 61. If the plurality of adducts 64 are successfully identified as one-dimensional arrangements having a pitch of 63, it can be judged that the chemical modification is one-dimensional arrangements.

In this case, the point of attachment of the adduct to the surface of the carbon material may be in the space 62 having a plurality of widths. The arrangement density of the chemical modification groups in this example can be determined by the number of columns arranged in one dimension. For example, in the case of forming a channel with a carbon material, the arrangement density of the chemical modification groups can be evaluated by how many columns of chemical modification groups are formed in a certain length thereof. The number of rows in the overall channel length can be easily made 50 or more, 100 or more, 200 or more. In the present invention, it is preferable that the predetermined channel length has at least 10 or more rows.

Next, fig. 6 (b) is a schematic diagram showing a case where chemical modification groups are arranged on the surface of a carbon material with a two-dimensional periodicity (lattice arrangement). This corresponds to the case where the STM observation image is observed in the predetermined field size 70. Fig. 6 (b) shows a two-dimensional array of rectangular shapes 72 in which one cell area is formed. The plurality of adducts 74 are schematically shown as being present one in each of the rectangular partitions, or as being present two in each of the rectangular partitions. Or schematically shows that the partition is empty due to the absence of adduct 74. Where the adduct is present is the presence of a partition 73. In contrast, the areas where the adducts were not present were blank areas 76.

The proportion of adduct in the face direction in this example is thus about 82% in 13 places/16 places. Preferably 85% or more, more preferably 90% or more. Of the 13 places where the adduct is present, 3 places are the repeat-adduct regions 75 where two adducts are present. That is, in the present invention, the proportion of the adduct in the plane direction means that the adduct is added to at least 5 to 15nm to the total surface area of the object to be surface-modified ² Proportion of adduct for one partition of the size.

Fig. 6 (c) is a schematic diagram showing a case where chemical modification groups are arranged on the surface of a carbon material in a two-dimensional periodic manner (honeycomb arrangement). This corresponds to the case where the STM observation image is observed in the predetermined field size 80. One unit area is constituted by a hexagonal shape 82. This example is also a form of two-dimensional periodic arrangement. The presence of one or two of each of the plurality of adducts 84 in the hexagonal partition is also schematically shown in this figure. Alternatively, the partition is shown schematically as empty due to the absence of the adduct 84. The unit area where the adduct exists is the existence of the partition 83.

The proportion of adduct in the face direction in this example is thus about 74% at 31 places/42 places. Preferably 80% or more, more preferably 90% or more. Of the 31 places where adducts exist, 4 places are the repeated addition regions 85 where two adducts exist.

In both cases of fig. 6 (b) and 6 (c), it is considered that the number of adducts (surface chemical modification groups) added per a predetermined unit area depends on the relative relationship between the size of the hollow in the film functioning as a mask and the size of the organic compound used as the adduct.

In the present invention, it is considered that a desired characteristic can be imparted to a carbon material such as graphene by skillfully performing positional control and chemical modification on the surface of the carbon material (see non-patent document 10). When a circuit is formed using the surface-modified carbon material according to the present invention, it is considered that a new electronic device having a band gap which is not zero and can be controlled by voltage or the like can be provided (see non-patent document 9).

As described above, the surface-modified carbon material of the present invention has new electrical characteristics, mechanical characteristics, optical characteristics, thermal characteristics, and the like, which have not been possessed by the conventional carbon materials such as graphene. This can be used for various applications such as Field Effect Transistors (FETs), sensors, light emitting elements, and catalysts.

For example, by forming a coating on SiO ₂ The surface-modified carbon material of the present invention can be formed on a substrate, a SiC substrate, or the like, and a device including the surface-modified carbon material of the present invention can be manufactured. For being preset in SiO ₂ Graphene such as a substrate and a SiC substrate (see non-patent documents 8 and 9) is chemically modified by the above method to prepare a surface-modified carbon material.

In this way, a novel electronic device can be formed by a method of surface-modifying the surface adduct of a carbon material selected from graphene, graphite, glassy carbon film, and film-like thermally decomposed carbon. That is, an attempt is made to chemically modify the surface of carbon compounds formed in several layers to obtain new properties and to implement a device. The graphene of the present invention includes 2 or more layers of multilayer graphene in addition to a single layer of graphene. For example, with respect to 2-layer graphene, there is commercially available a product manufactured by transferring a film material formed by a CVD method onto a substrate.

It is particularly preferable to construct a mechanism as an electronic device by forming a channel using a monolayer of graphene chemically modified to have a predetermined periodicity.

Fig. 6 d is a schematic plan view of a basic form of an electronic device 300 in which electrodes 305 and 306 are formed at both ends of a 6-membered ring planar arrangement 302 of a surface-modified carbon material in which chemical modification groups 304 are arranged in a one-dimensional periodic manner on the surface of a carbon material (graphene nanoribbon) processed into a fine sheet shape, which is supported on a substrate 307. The channel length of the electronic device 300 is denoted by L and the channel width is denoted by W.

In the structure of the figure, an arrangement (one-dimensional periodicity) of adducts arranged parallel to the channel direction may be provided between the electrodes on both sides in 10 columns, 20 columns. Furthermore, the adduct 304 may be set to a desired number corresponding to the relative proportional relationship of the channel length to the organic compound (alkane) molecule length. In addition, the width of the graphene nanoribbons may also be adjusted. In addition, the present figure shows a state after removing the thin film serving as a mask.

Fig. 6 e is a schematic plan view of a basic form of an electronic device 400 in which electrodes 405 and 406 are formed at both ends of a 6-membered ring planar arrangement 402 of a surface-modified carbon material in which chemical modification groups 404 are periodically arranged on the surface of a fine sheet-like carbon material (graphene nanoribbon) supported on a substrate 407 as another example of the present invention.

In the structure of this figure, an adduct 404, which is added to a two-dimensionally periodic thin film, between electrodes on both sides is added to a predetermined cell area (90 nm ² ) The case of almost average arrangement is shown in the plane. In the present invention, in order to show the positional relationship with each other, a periodic assembly 403 showing a two-dimensional periodicity, which is used as a mask when the chemical modifier 404 is added, is displayed so as to overlap with the 6-membered ring planar arrangement 402. In the example of the present figure, the ratio in the effective area covered by the mask is 46 places/48 places=about 96% except for the portion on the edge side. In addition, there are four where two chemical modification groups are added to one unit area.

Fig. 6 (f) shows a schematic cross-sectional view of a sensor electronic device 500 as an example of the present invention. The graphene 560 is transferred and supported on the surface of the silicon substrate 570 serving as an insulating substrate. Then, the surface of graphene 560 is chemically modified by the above-described manufacturing method. The shape and size of graphene in the opposite direction are processed and adjusted, and electrodes 510 and 520 are formed at both ends of the graphene portion as a channel so that the contact resistance becomes sufficiently small. Alternatively, the graphene 560 may be directly formed on the silicon substrate 570.

As for the chemical modification group 540, a reactive group may be added in advance to react with a chemical substance in a gas. However, it is difficult for the chemical modification group to withstand an external force of a predetermined magnitude or more. Therefore, a substance which hardly affects physical properties may be provided as the protective layer 550 on the upper portion of the graphene portion which is a channel, so that the adduct and the graphene are held. For example, as a material capable of protecting the surface of the carbon material to some extent, a layer of alkane exhibiting insulation properties may be mentioned.

Then, the control circuit is connected to the electrode, and a chemical substance that reacts with the chemical modification group 540 added to the surface of the channel portion can be detected. This is detected because of the variation in the electrical characteristics in the channels.

Next, fig. 6 (g) shows a basic configuration of a bottom gate electronic device 600. The electronic device 600 has a 3-terminal structure, and includes an insulating film 650, a substrate 630 using low-resistance doped Si, which serves as both a gate electrode and a substrate, and a terminal 630T for applying a gate potential, on the lower side of the electrode 610, the electrode 620, and the graphene 660 serving as a channel.

When the channels of the electronic device 600 are arranged between the electrodes, the arrangement in the main axis direction in the plane may be determined in advance so that the end structure of the graphene in the channel direction may be a saw-tooth structure or a reclining chair structure that can obtain the desired semiconductor characteristics. Further, a method of protecting a surface-chemically modified carbon material used as a passage by airtight sealing and blocking outside air or the like may be applied.

Further, it is considered that the addition product on the graphene surface can be used as a catalyst by supporting metal nanoparticles such as cobalt, manganese, and iron. For example, by incorporating an acidic or basic functional group into a chemical modification group in advance, the chemical modification group is periodically introduced onto the surface of a carbon material, and a material exhibiting a high catalytic effect with respect to substrate selectivity is expected. In addition, by introducing a site coordinated to a metal or the like into a chemical modification group in advance, metal ions and nanoparticles are immobilized at the coordinated site, and thus a material exhibiting various catalytic actions is expected. In this case, it is also expected that the reaction efficiency and the catalyst life are improved due to the interaction between the steric structure of the carbon material and the catalyst and electrons.

Examples

The first embodiment of the present invention will be described below. The first embodiment refers to the case where the film has "one-dimensional periodicity". Embodiment 2 described below is a case where the film has a "two-dimensional periodicity".

First, the first embodiment is described in detail according to examples 1-1 to 1-5, but the present invention is not limited to these examples.

First embodiment

The structure and dimensions of the electrochemical cells used in the following examples and comparative examples are shown. The cell height composed of PTFE was "upper: 35mm "and" lower: 3mm "," upper inner diameter:"and" lower inner diameter: />". An electrochemical cell 20 having a working electrode 21 (carbon material) at the lower portion and a counter electrode 22 and a reference electrode 23 at the upper portion (see fig. 3 (a) to (c)). Further, various measurements in examples and comparative examples were performed by the following methods.

(1) Observation by Scanning Tunneling Microscope (STM)

Observation by a Scanning Tunneling Microscope (STM) was performed using Nanoscope V (Bruker AXS). STM probes were mechanically cut from Pt/Ir (composition ratio 8:2) alloy available from Takara Shuzo Co., ltd. Most images are in tunnel current I _t (30 pA-60 pA) and bias voltage V _b Obtained at (-600 mV), height information of the sample was recorded.

The FFT processing of the STM observation image was performed using SPIP image analysis software (registered trademark) of image metering company (Image Metrology A/S). Fig. 1 (b) is an explanatory diagram showing an outline of STM observation employed for examining the surface chemical modification state of the carbon material according to the present invention.

In addition, in STM observation, a certain result can be obtained even if the object to be detected is placed in the atmosphere. However, it is generally known that the resolution is better when the object to be detected is placed in a liquid. Thus, in the STM observation in the following examples and the like, the object to be detected was placed in a liquid of tetradecane and phenyloctane, and the STM observation was performed.

(2) Raman spectroscopy

Raman spectroscopy was performed using XploRA (registered trademark) super confocal raman spectrometer (Plus Confocal Raman Microscope) manufactured by horiba corporation. Nd-YAG laser (532 nm) was focused with a 50-fold objective lens and irradiated to the dried sample surface. Raman scattering was focused by the same objective lens and detected with a CCD detector. From raman spectra obtained at 16 different places of the same sample, the integrated intensities of the D and G bands were calculated, respectively, and Id/Ig was calculated. The average value of Id/Ig at 16 places was used as the Id/Ig of the sample (see FIG. 3 (g) above).

In addition, 1590cm of Raman spectrum of the chemically modified carbon material surface was used ^-1 The intensity of the G band peak appearing nearby (I _G ) And 1350cm ^-1 The intensity of the nearby D band peak (I _D ) Ratio (I) _D /I _G ). The G band is a vibration mode derived from the structure of the carbon material. The higher the crystallinity, the stronger the peak intensity. The D band is derived from the structure of the carbon material as the G band, but is not an intrinsic vibration mode, and reflects a defect caused by the presence of a modifying group based on surface modification. The spectral intensity becomes stronger to the extent corresponding to the defect. The following operations were all performed at room temperature.

Examples 1 to 1

Soaking high-orientation pyrolytic graphite (HOPG, ZYB grade, manufactured by Maifanitum high new material (Momentive Performance Materials)) in dichloromethane and N-hexane, cleaning, and applying adhesive tape (N)ittotape, no. 3800K) is peeled off and then mounted as a working electrode 21 in the electrochemical cell 20. mu.L of fifty alkane (C) was pipetted into a micropipette ₅₀ H ₁₀₂ ) The concentration is 1.0X10 ^-5 A solution of M in tetradecane is added to HOPG within electrochemical cell 20. After 10 minutes, 4.9mL of a 50mM hydrochloric acid solution having a 3, 5-di-t-butylaniline concentration of 1mM and 0.1mL of a 0.1M aqueous sodium nitrite solution were added to the sampling tube and mixed with shaking for 30 seconds to prepare 3, 5-di-t-butylbenzene diazonium chloride (TBD). 500 μl of this solution was carefully added with a micropipette over the tetradecane layer on HOPG in a manner that did not disrupt the tetradecane layer. Thereafter, all of the remaining solution described above is added to electrochemical cell 20.

After 3 minutes from the start of mixing, the mixture was subjected to a cyclic voltammetry (612 DA electrochemical analyzer, manufactured by ALS/CH instruments Co.) at a temperature of-0.7V to +0.1V (Ag/Ag) ⁺ ) The cyclic voltammogram was measured by repeating the scanning 5 times in the potential range of (2).

After the scanning, the aqueous layer was removed by micropipette, 5.0mL of ultrapure water was added to the electrochemical cell 20 by micropipette in such a manner as not to disturb the tetradecane layer, and then the ultrapure water was removed and the surface of the tetradecane layer was washed. This washing operation was performed twice in total.

HOPG was removed from the electrochemical cell 20 and STM observations were made at the interface of the surface residual tetradecane solution and HOPG. After STM observation, the surface was dried with warm air from a blower to remove tetradecane, and Raman spectrum was measured.

The resulting cyclic voltammogram is shown in fig. 7 (a). Irreversible reduction waves were observed at-340 mV and-460 mV in the first scan (bottom curve). Thus, it is apparent that aryl diazonium salts are reduced and free radical species are generated.

FIG. 7- (b) and (c) show the STM observation image (V) _bias ＝-600mV，I _set =30pa). The light spot in the image is caused by aryl groups added to HOPG. The spots were observed to be aligned like lines, corresponding to the layer structure of fifty-carbon attached as a thin film to HOPG (fig. 7- (c)). It was found that the multiple spots were aligned in a straight line along the fifty molecular column (fig. 7- (b)). The upper right part of FIG. 7- (b) shows The image shown is a fourier transformed image of the STM observation image as obtained by fourier processing (FFT). The fourier transform image is enlarged to fig. 7 (e). From the fourier transform image, it was found that the positions of the plurality of light spots were arranged in a periodic manner with a pitch of 6.8 nm.

From the above, the HOPG treated above was a surface-modified carbon material having aryl groups added to the graphite surface, and the periodicity corresponding to many aryl groups addition positions was confirmed in one-dimensional direction in the fourier transform image of the STM observation image of the surface.

The raman spectrum obtained is shown in fig. 7 (d). In the Raman spectrum, a spectrum of sp is observed in the graphite lattice ³ The D band, id/Ig, caused by the presence of carbon is 0.036.

Examples 1 to 2

Highly oriented pyrolytic graphite (HOPG, ZYB grade, manufactured by michigan high new material (Momentive Performance Materials)) was immersed in methylene chloride and n-hexane, washed, peeled off with a tape (nitlotape, no. 3800K), and incorporated as a working electrode 21 in an electrochemical cell 20. mu.L of tetradecane (C) was pipetted into a micropipette ₄₀ H ₈₂ ) The concentration is 3.5X10 ^-5 A solution of M in tetradecane is added to HOPG within electrochemical cell 20.

After 10 minutes, 4.9mL of a 50mM hydrochloric acid solution having a 3, 5-di-t-butylaniline concentration of 1mM and 0.1mL of a 0.1M aqueous sodium nitrite solution were added to the sampling tube and mixed with shaking for 30 seconds to prepare 3, 5-di-t-butylbenzene diazonium chloride (TBD). 500 μl of this solution was carefully added with a micropipette over the tetradecane layer on HOPG in a manner that did not disrupt the tetradecane layer. Thereafter, all of the remaining solution described above is added to electrochemical cell 20.

After 3 minutes from the start of mixing, the mixture was subjected to a cyclic voltammetry (612 DA electrochemical analyzer, manufactured by ALS/CH instruments Co.) at a temperature of-0.7V to +0.1V (Ag/Ag) ⁺ ) Is repeatedly scanned 5 times under the potential range of (2).

FIG. 8- (a) shows the STM observation image (V _bias ＝-600mV，I _set =50pa). As in example 1-1 using fifty-alkane, it can be confirmed from fig. 8- (a) that a plurality of light spots are placed in the gaps of the forty-alkane layer structure. Fig. 8- (b) is a fourier transform image obtained by subjecting the STM observation image to fourier processing (FFT). From the fourier transform image, it was found that the existence positions of the spots were arranged in a periodic manner with a pitch of 5.8 nm.

From the above, the HOPG treated above is a surface-modified carbon material in which aryl groups are added to the graphite surface. Then, in the fourier transform image of the STM observation image of the surface, it was confirmed that periodicity corresponding to many aryl addition positions was observed in one-dimensional direction. The resulting raman spectrum observed a D band with Id/Ig of 0.029.

Examples 1 to 3

Highly oriented pyrolytic graphite (HOPG, ZYB grade, manufactured by michigan high new material (Momentive Performance Materials)) was immersed in methylene chloride and n-hexane, washed, peeled off with a tape (nitlotape, no. 3800K), and incorporated as a working electrode 21 in an electrochemical cell 20.

mu.L of triacontane (C) was pipetted into a micropipette ₃₀ H ₆₂ ) The concentration is 1.2 multiplied by 10 ^-2 A solution of M in tetradecane is added to HOPG within electrochemical cell 20. After 10 minutes, 4.9mL of a 50mM hydrochloric acid solution having a 3, 5-di-t-butylaniline concentration of 1mM and 0.1mL of a 0.1M aqueous sodium nitrite solution were added to the sampling tube and mixed with shaking for 30 seconds to prepare 3, 5-di-t-butylbenzene diazonium chloride (TBD). 500 μl of this solution was carefully added with a micropipette over the tetradecane layer on HOPG in a manner that did not disrupt the tetradecane layer. Thereafter, all of the remaining solution is added to the electrochemical cell 20 。

FIG. 9- (a) shows the STM observation image (V _bias ＝-600mV，I _set =20pa). As in example 1-1 using fifty-alkane, it was confirmed from FIG. 9- (a) that a plurality of light spots were placed in the gaps of the layer structure of triacontane. The image shown in the upper right part of fig. 9- (a) is a fourier transform image obtained by subjecting the STM observation image to fourier processing (FFT). The fourier transform image is enlarged to fig. 9- (b). From the fourier transform image, it was found that the positions of the plurality of light spots were arranged in a periodic manner with a pitch of 4.1 nm.

From the above, the HOPG treated above was a surface-modified carbon material having aryl groups added to the graphite surface, and the periodicity corresponding to many aryl groups addition positions was confirmed in one-dimensional direction in the fourier transform image of the STM observation image of the surface. The resulting raman spectrum observed a D band with Id/Ig of 0.029.

Examples 1 to 4

Raman spectra of single-layer graphene (manufactured by luffm jet of the company of graphene platform, japanese) produced by CVD method on copper foil was measured. After raman spectroscopy, the single-layer graphene was incorporated into the electrochemical cell 20 together with copper foil as the working electrode 21. mu.L of triacontane (C) was pipetted into a micropipette ₃₀ H ₆₂ ) The concentration is 1.2×10 ^-2 A solution of M in tetradecane is added to the monolayer graphene within electrochemical cell 20.

After 10 minutes, 4.9mL of a 50mM hydrochloric acid solution having a 3, 5-di-t-butylaniline concentration of 1mM and 0.1mL of a 0.1M aqueous sodium nitrite solution were added to the sampling tube and mixed with shaking for 30 seconds to prepare 3, 5-di-t-butylbenzene diazonium chloride (TBD). 500 μl of this solution was carefully added with a micropipette over the tetradecane layer on the monolayer graphene in a manner that did not disrupt the tetradecane layer. Thereafter, all of the remaining solution described above is added to electrochemical cell 20.

The copper foil and the single-layer graphene were removed from the electrochemical cell 20, and STM observation was performed at the interface between the tetradecane solution remaining on the surface and the single-layer graphene. After STM observation, the surface was dried with warm air from a blower to remove tetradecane, and Raman spectrum was measured.

The resulting cyclic voltammogram is shown in FIG. 10- (a). Irreversible recovery waves were observed at-420 mV in the first scan (bottom curve).

The STM observation image (V) obtained is shown in FIGS. 10- (b), - (c) and (f) _bias ＝-600mV，I _set =30pa). As in examples 1 to 3 using HOPG, it was confirmed from fig. 10- (b), - (c) and (f) that a plurality of spots were placed in the gaps of the triacontane layer structure.

The image shown in fig. 10- (g) is a fourier transform image obtained by subjecting the STM observation image to fourier processing (FFT). From the fourier transform image, it is known that the arrangement of the plurality of light spots has a periodicity exhibiting a pitch of 4.6 nm. From the above, it was found that the single-layer graphene treated as described above is a surface-modified carbon material in which aryl groups are added to the graphite surface. Then, in the fourier transform image of the STM observation image of the surface, it was successfully confirmed that the periodicity corresponding to the plurality of aryl addition positions was exhibited in the one-dimensional direction.

Fig. 10- (d) shows raman spectra obtained for single-layer graphene before treatment by an electrochemical cell, and fig. 10- (e) shows raman spectra obtained for single-layer graphene after treatment by an electrochemical cell. The D band was observed in the Raman spectrum shown in FIG. 10- (e), with Id/Ig of 1.9.

Examples 1 to 5

The same procedure was followed as in examples 1 to 4. First, raman spectra of single-layer graphene on a Cu substrate fabricated by a CVD method were measured before surface modification. After measuring raman spectra, the single layer graphene is loaded into an electrochemical cell. A solution of fifty-alkane in tetradecane (20. Mu.L, 1.0X10) was pipetted ^-5 ) Added to a monolayer of graphene within an electrochemical cell.

After 10 minutes, a solution of 3, 5-di-t-butylaniline (1 mM) in hydrochloric acid (50 mM,4.9 mM) and an aqueous solution of sodium nitrite (0.1M, 0.1 mL) were added to the sampling tube and mixed with shaking for 30 seconds with stirring. A portion (500 μl) of this solution was carefully added from the micropipette over the tetradecane layer on the monolayer graphene in a manner that did not disrupt the tetradecane layer.

Thereafter, the remaining solution was added in its entirety to the electrochemical cell. Cyclic voltammograms were determined 3 minutes after the start of mixing. After the measurement, the aqueous layer was removed by a micropipette, ultrapure water (5.0 mL) was added to the electrochemical cell by a micropipette so as not to disturb the tetradecane layer, and then the surface of the tetradecane layer was washed by removing ultrapure water.

This washing operation was performed twice (10 mL). And taking out the single-layer graphene from the electrochemical cell, and performing STM observation at the interface of the tetradecane solution remained on the surface and the single-layer graphene. Fig. 11 is data corresponding to this example, in which fig. 11- (a) is a cyclic voltammogram of this example, and fig. 11- (b), - (c), and- (d) are STM observation images obtained in this example.

Comparative examples 1 to 1

mu.L of 1-phenyloctane was added to HOPG in the electrochemical cell 20 with a micropipette. After 10 minutes, 4.9mL of a 50mM hydrochloric acid solution having a 3, 5-di-t-butylaniline concentration of 1mM and 0.1mL of a 0.1M aqueous sodium nitrite solution were added to the sampling tube and mixed with shaking for 30 seconds, to prepare 3, 5-di-t-butylbenzene diazonium chloride (TBD). 500 μl of this solution was carefully added with a micropipette over the 1-phenyloctane layer on HOPG in a manner that did not disrupt the 1-phenyloctane layer. Thereafter, all of the remaining solution described above is added to electrochemical cell 20.

After the scanning, the aqueous layer was removed by micropipette, 5.0mL of ultrapure water was added to the electrochemical cell 20 by micropipette in such a manner as not to disturb the 1-phenyloctane layer, and then the ultrapure water was removed and the 1-phenyloctane layer surface was washed. This washing operation was performed twice in total.

The HOPG was removed from the electrochemical cell 20 and STM observations were made at the interface of the remaining 1-phenyl octane on the surface with the HOPG. After STM observation, the surface of the glass was dried with warm air from a blower to remove 1-phenyl octane, and Raman spectra were measured. The resulting cyclic voltammogram is shown in FIG. 12- (a). In the first scan (lowest curve) it was observed that the sample was taken at-140 mV (Ag/Ag ⁺ ) As an irreversible reduction wave at the peak top.

FIG. 12- (b) shows the STM observation image (V _bias ＝-600mV，I _set =30pa). The flare in the image was caused by the aryl group added to HOPG, and it was confirmed that the aryl group was added to HOPG. However, no regularity is found in the existing positions of the plurality of spots appearing on the image. FIG. 12- (b)The upper right portion of (a) is shown as a fourier transformed image of the STM observation image after fourier processing (FFT). The fourier transform image is enlarged to fig. 12- (d). With respect to the fourier transform image, periodicity is not confirmed in the existence position of the light spot.

From the above, the HOPG treated above was a surface-modified carbon material in which aryl groups were added to the graphite surface, but it was confirmed that periodicity corresponding to many aryl addition positions was not observed in the fourier transform image of the STM observation image of the surface. The resulting raman spectrum is shown in fig. 12- (c). Band D was observed, id/Ig was 0.11.

Comparative examples 1 to 2

mu.L of 1,2, 4-trichlorobenzene was added to HOPG in the electrochemical cell 20 with a micropipette. After 10 minutes, 4.9mL of a 50mM hydrochloric acid solution having a 3, 5-di-t-butylaniline concentration of 1mM and 0.1mL of a 0.1M aqueous sodium nitrite solution were added to the sampling tube and mixed with shaking for 30 seconds, to prepare 3, 5-di-t-butylbenzene diazonium chloride (TBD). 500 μl of this solution was carefully added with a micropipette over the 1,2, 4-trichlorobenzene layer on HOPG in a manner that did not disrupt the 1,2, 4-trichlorobenzene layer. Thereafter, all of the remaining solution described above is added to electrochemical cell 20.

After 3 minutes from the start of mixing, the mixture was subjected to a cyclic voltammetry (612 DA electrochemical analyzer, manufactured by ALS/CH instruments Co.) at a temperature of-0.7V to +0.1V (Ag/Ag) ⁺ ) The cyclic voltammogram was measured by repeating the scanning 5 times in the potential range of (2). After the scanning, the aqueous layer was removed by micropipette, 5.0mL of ultrapure water was added to the electrochemical cell 20 by micropipette in such a manner as not to disturb the 1,2, 4-trichlorobenzene layer, after which the ultrapure water was removed and the 1,2, 4-trichlorobenzene layer surface was washed. This washing operation was performed twice in total.

The HOPG was removed from the electrochemical cell 20 and STM observations were made at the interface of the residual 1,2, 4-trichlorobenzene on the surface with the HOPG. After STM observation, 1,2, 4-trichlorobenzene on the surface was dried and removed by warm air of a blower, and Raman spectrum was measured.

From the cyclic voltammogram obtained, it was observed that the voltage of the sample was measured at-140 mV (Ag/Ag ⁺ ) As an irreversible reduction wave at the peak top.

From the obtained STM observation image, a flare due to an aryl group was confirmed in the same manner as in comparative example 1-1. However, no regularity is found in the presence positions of the plurality of spots. The fourier transform image obtained by fourier processing (FFT) from the STM observation image has no periodicity confirmed in the arrangement of the plurality of light spots.

From the above, the HOPG treated above was a surface-modified carbon material in which aryl groups were added to the graphite surface, but it was confirmed that periodicity corresponding to many aryl addition positions was not observed in the fourier transform image of the STM observation image of the surface. The resulting raman spectrum observed a D band with an Id/Ig of 0.13.

Comparative examples 1 to 3

mu.L of tetradecane was added to HOPG in the electrochemical cell 20 with a micropipette. After 10 minutes, 4.9mL of a 50mM hydrochloric acid solution having a 3, 5-di-t-butylaniline concentration of 1mM and 0.1mL of a 0.1M aqueous sodium nitrite solution were added to the sampling tube and mixed with shaking for 30 seconds, to prepare 3, 5-di-t-butylbenzene diazonium chloride (TBD).

500 μl of this solution was carefully added with a micropipette over the tetradecane layer on HOPG in a manner that did not disrupt the tetradecane layer. Thereafter, all of the remaining solution described above is added to electrochemical cell 20. After 3 minutes from the start of mixing, the mixture was subjected to a cyclic voltammetry (612 DA electrochemical analyzer, manufactured by ALS/CH instruments Co.) at a temperature of-0.7V to +0.1V (Ag/Ag) ⁺ ) The cyclic voltammogram was measured by repeating the scanning 5 times in the potential range of (2).

HOPG was removed from the electrochemical cell 20 and STM observations were made at the interface of tetradecane remaining on the surface and HOPG. After STM observation, the surface was dried with warm air from a blower to remove tetradecane, and Raman spectrum was measured. From the cyclic voltammogram obtained, it was observed that the voltage of the sample was measured at-140 mV (Ag/Ag ⁺ ) As an irreversible reduction wave at the peak top.

From the obtained STM observation image, a flare due to an aryl group was confirmed in the same manner as in comparative example 1-1. However, no regularity is found in the presence positions of the plurality of spots. With regard to a fourier transform image obtained by subjecting the STM observation image to fourier processing (FFT), periodicity is not confirmed among a plurality of spot positions.

From the above, the HOPG treated above was a surface-modified carbon material in which aryl groups were added to the graphite surface, but it was confirmed that periodicity corresponding to many aryl addition positions was not observed in the fourier transform image of the STM observation image of the surface. The resulting raman spectrum observed a D band with an Id/Ig of 0.13. The above results are shown in table 2 below. In these examples, it is believed that the periodic spacing will vary correspondingly with the molecular length of the alkane used.

TABLE 2

Next, the alkane that can be preferably used in the first embodiment of the present invention is shown in table 3 below.

TABLE 3

Carbon number	Name of the name
		C＝15	Pentadecane
C＝16	Hexadecane
		C＝17	Heptadecane
C＝18	Octadecane (Octadecyl)
		C＝19	Nonadecane
C＝20	Eicosane (icosane)
		C＝21	Diundecane
C＝22	Behenic acid dodecane
		C＝23	Behenic acid dodecane
C＝24	Tetracosane (II)
		C＝25	Cyclopentadecane
C＝26	Hexacosane (hexacosane)
		C＝27	Diheptadecane
C＝28	Octacosane
		C＝29	Icosahederane
C＝30	Triacontane
		C＝40	Tetradecane (P)
C＝50	Isopitane (P)
		C＝60	Hexadecane
C＝70	Heptadecane
		C＝80	Octadecane

As an example of the organic compound applicable to the first embodiment of the present invention, the alkane listed in table 3 is a linear saturated hydrocarbon and has a carbon number of 15 to 80. Similarly, the alkane derivative may have 10 to 80 carbon atoms. The organic solvent may be a compound for dissolving the alkane or alkane derivative.

For example, an alkane having relatively small carbon number such as pentane having 5 carbon atoms, hexane having 6 carbon atoms, heptane having 7 carbon atoms, octane having 8 carbon atoms, nonane having 9 carbon atoms, decane having 10 carbon atoms, undecane having 11 carbon atoms, dodecane having 12 carbon atoms, tridecane having 13 carbon atoms, or tetradecane having 14 carbon atoms can be preferably used as the organic solvent.

Preferably, an alkane having a high boiling point and having a carbon number difference of 4 or more relative to the alkane used for forming the film is selected and used. In addition, the solution may contain a compound other than an alkane within a range that does not affect the alkane monolayer as a mask.

The first embodiment described above, which includes examples 1-1 to 1-5, is a surface-modified form of an adduct having a one-dimensional periodic structure. Next, a second embodiment of the present invention in which the surface of the adduct having a two-dimensional periodic structure is modified will be described.

Second embodiment

FIG. 16 shows a schematic structural diagram of 1,3, 5-tris (4-carboxyphenyl) benzene (H3 BTB) which is an organic compound that can be used in the present embodiment.

To verify whether or not the present embodiment is applicable, observation of an STM observation image of a simple assembly is performed. In addition, optimization of the structure of the assembled body centered on the void was performed by molecular mechanical calculation (MM calculation) of the structure based on H3 BTB. As a result, the predicted void diameter was about 3.4nm. The pore size is large enough for the addition reaction of aryl radicals to occur.

Then, after an attempt is made as to whether or not a periodic structure can be formed using H3BTB, although a defective structure is found in a part, it has a relatively large area size. (200 nm. Times.200 nm or more). Then, regarding the size of the voids of the single unit, the length (a=b) of the hexagon inscribed in the voids was 3.2nm, and regarding the hexagon forming the voids, the angle between the adjoining sides was 60 degrees.

An experiment of carbon surface chemical modification was performed using H3BTB capable of forming a thin film having two-dimensional periodicity. STM observations were made by forming a thin film on a carbonaceous film in the same manner as in examples 1-1 to 1-5. The reaction was carried out under experimental conditions in which pelargonic acid (n-Nonoic Acid (NA)) was used as a solvent, and a saturated solution of 2.5% was used at room temperature.

[ chemical formula 11]

[ experimental conditions ]

With dichloromethane (CH) ₂ Cl ₂ ) And washing with n-hexane, and loading the stripped HOPG into an EC cell. To this was added 20. Mu.L of H3BTB/NA solution (2.5% saturation) and allowed to stand for 10 minutes. Further mixing 3,4, 5-Trimethoxyaniline (TMA) aqueous hydrochloric acid (3 mM,4.9 mL) and NaNO ₂ Aqueous solution (0.1 m,0.3 ml) was mixed and after 30 seconds, the aqueous solution was slowly added to the EC cell with a micropipette.

After 3 minutes of mixing, the reduction operation was performed using CV. The scanning range is +0.20V to-0.70V, the scanning speed is 0.1V/second, and the scanning times are 1. As described above, TMA is a compound which is not multilayered and can chemically modify the surface of a carbon material almost uniformly, similarly to TBD.

After the completion of the reduction operation, the aqueous solution was removed by a micropipette, and the EC cell was washed twice with ultrapure water. The HOPG was taken out of the EC cell and STM observations were made directly.

Subgraph (a) and subgraph (c) of fig. 17 (a) show STM observation images and raman spectrum data after electrochemical treatment. And sub-graph (b) is the cyclic voltammogram obtained. The first scanning wave and the second scanning wave are arranged from bottom to top.

Comparative examples 2-1 and 2-2 were cases where the chemical modifier was TBD and the content in the liquid medium was low. Since the formed film does not exhibit two-dimensional periodicity, it is known that the TBD does not satisfy the necessary content condition.

In example 2-1, a film which can be considered as a periodic assembly was successfully formed by using 3mM TMA. Further, the results of the above calculation were obtained with the chemical modification ratio of HOPG being 70% or more.

Next, in example 2-2, the mixture was dissolved in 1-DBA-OC 6 of Phenyl Octane (PO) was used as mask and TMA was used as chemical modification substance. The concentration of DMA-OC6 was 2.0X10 ^-5 . TMA aqueous hydrochloric acid (2 mM,4.8mL, hydrochloric acid: in 50 mM) and NaNO ₂ The aqueous solution (0.1 m,0.2 ml) was mixed and after stirring for 30 seconds, the aqueous solution was slowly added to the EC cell with a micropipette.

After STM observation of the chemically modified HOPG (sub-graph (a) of FIG. 17 (b)), it was found that a hexagonal period exists in the Fourier transform image of the STM observation image (FIG. 17 (b)). In addition, an Id/Ig of 0.085 and a proportion of 78% were obtained.

In this example, the concentration of the chemical modification compound contained in the aqueous electrolyte solution 24 is set in the range of 0.2 to 10 mmol/L. The combination of the chemical modification compound with the thin film material, the correlation of the chemical modification group with the size in the periodic structure, and the like may be related as parameters. When the ratio is 70% or more, the concentration of the chemical modification compound is preferably 2 to 7 mmol/L in order to perform chemical modification at a predetermined reaction rate. Even more preferably 3 to 6 mmol/L. If the concentration of the chemical modification compound is within the above range, the chemical modification compound reacts well with the surface of the carbon material represented by graphene or the like, or graphite, as the working electrode 21, and a sufficient amount of chemical modification groups exhibiting periodicity and simultaneously are easily added to the surface of the carbon material such as graphene. The experimental results of this example are shown in table 4 below.

TABLE 4

Next, another specific example will be described in which DBA is used as a single unit that can form an assembly. First, fig. 18 and 19 show DBA-OC4 to DBA-OC10 having different pore sizes. For the 4 organic compounds, the pore sizes were 1.4nm, 1.6nm, 2.1nm, 2.7nm, respectively. Although the individual voids vary in size, a single unit may be formed.

Of these 4, three types of DBA-OC 10-OC 6 were successfully confirmed to exhibit periodic structures. In addition, the value of Id/Ig in the Raman spectrum can also be verified. The concentration of DBA, H3BTB, etc. in the solution for forming a thin film having a periodic structure is preferably 1. Mu. Mol/L or more and 1 mmol/L or less.

Fig. 20 shows STM observation images and fourier transform images of DBAOC10, DBAOC8, and DBAOC 6. Successful confirmation of the periodic structure from the fourier transformed image was made.

Fig. 21 is a drawing cited from the above-mentioned non-patent document 6, and shows an organic compound group having DBA as a central skeleton, which is applicable to the present invention. If organic compounds having different branch lengths are used as a single unit (fig. 21- (a)), the size of the pores in the resulting aggregate can be controlled (refer to fig. 21- (b) - (e)).

The assembly may be formed using substantially the same organic compound. The voids in the resulting assembly exhibit a generally polygonal shape, preferably a hexagonal shape. This is because the hexagonal shape easily forms a uniform and stable assembly on the surface of the carbon material. Further preferably, the assembly void has a regular hexagonal shape.

The sub-image (a) of fig. 22 is a reference from the image of the above-mentioned non-patent document 6, and is a surface observation photograph. Subgraph (b) is an STM image. And sub-figure (c) is a schematic structural diagram of a single unit formed from an organic compound. Fig. 23 is an explanatory diagram showing the structure of other organic compound groups that can form a two-dimensional periodic structure.

Finally, a case where a two-dimensional periodic structure in the film shows a star-shaped arrangement structure will be described. When the organic compounds are arranged in a plurality on a two-dimensional surface, the organic compounds are known to have a predetermined polygon or star-shaped polygon. An example of an organic compound which becomes the basis of an assembly in the form of a star-shaped regular hexagon, i.e., a cage structure, is shown in fig. 24.

Specifically, sub-graph (a) of FIG. 24 shows a diamond fused ring type dehydrobenzo [12 ]]Rotaene (bisDBA) derivative (r=c ₁₀ H ₂₁ 、C ₁₂ H ₂₅ 、C ₁₄ H ₂₉ C ₁₆ H ₃₃ ) Chemical junction of (2)The structural formula, subplot (b), shows the STM observation image. Sub-graph (c) shows the relative positions of the star-shaped hexagons in sub-graph (b). In the same manner as in fig. 5 (a), in the sub-view (c) of fig. 24, the size of the void is 200S, and the size in the transverse and longitudinal directions of the void is denoted by a cross 200 XY.

Finally, an explanatory diagram showing a compound that can form an assembly exhibiting two-dimensional periodicity in the case of having a double ring structure is shown in fig. 25. An assembly of relatively large dimensions can be formed for use in the present invention.

Industrial applicability

In the surface-modified carbon material of the present invention, although not completely, it is considered that the graphene nanoribbon conjugated system exists at the surface site of the carbon material typified by graphite and graphene. Therefore, the surface-modified carbon material may exhibit anisotropic conductivity (conductivity along a conjugated system) in addition to band gap control.

Therefore, the surface-modified carbon material of the present invention is possible for use as a Field Effect Transistor (FET) and a molecular electronic material. For example, it is possible to use the chemical modification groups (functional groups) periodically introduced into graphene and graphite in a molecular sensor with high selectivity and high sensitivity, and to use the catalyst and information storage medium based on surface alignment control of metal nanoparticles.

It is needless to say that the present invention can be applied to carbon materials such as carbon nanotubes, in addition to graphene, graphite, glassy carbon films, and membranous thermally decomposed carbon. In this case, it is considered that a local region of the carbon material having a curved surface is chemically modified. In addition, the carbon material having a curved surface may be modified in design to enable the chemical reaction.

Symbol description

1. 41 carbon material

2. 12 straight chain alkane

3. 13, 43 film

30. 105a, 205a basic skeleton

33U assembly (hexagonal Structure Using DBA)

4. 14, 44 chemical modification group

5. 15a, 15b, 15c, 45 surface-modified carbon material

20 electrochemical cell

21 working electrode

22 pairs of electrodes

23 reference electrode

24 liquid medium

25 electrolyte aqueous solution

26 organic compound-carbon Material Complex

100 carbon material covered with two-dimensional periodic compound (conventional example)

102. 112, 122 six-membered ring planar arrangement (surface portion of carbon material)

105b, 205b branch

110. 120 electronic device (existing example)

200 carbon material covered by two-dimensional periodic mask

203. 403 periodic assembly

300. 400, 500 electronic device (inventive)

305. 306, 405, 406, 510, 520, 610, 620 electrodes

550 protective layer

560. 660 graphene

630 substrate (highly doped Si substrate)

650 gate insulating film

Claims

1. A surface-modified carbon material having a plurality of aryl groups on at least a part of the surface thereof, wherein the surface-modified carbon material is selected from the group consisting of graphene, graphite, a glassy carbon film, and a film-like thermally decomposed carbon,

wherein the aryl group is represented by the following formula (1),

[ chemical formula 1]

In the formula (1), R ¹ 、R ² And R is ³ Each independently is alkyl, alkenyl, alkynyl, aryl, OR, COOH, SOOH, SOONH ₂ 、NO ₂ 、COOR、SiR ₃ 、H、F、Cl、Br、I、OH、NH ₂ 、NHR、NR ₂ CN, CONHR or COH, wherein R is alkyl, alkenyl, alkynyl, aryl or halogen substituent thereof,

in the fourier transform image of the scanning probe microscope image of the surface, one-dimensional or two-dimensional periodicity corresponding to the plurality of addition positions of the aryl group can be observed.

2. The surface-modified carbon material according to claim 1, wherein the one-dimensional periodicity corresponds to a pitch of 2 to 10nm.

3. The surface-modified carbon material according to claim 1 or 2, wherein the carbon material is graphene, and Id/Ig for G-band intensities Ig and D-band intensities Id in raman spectra of the surface is 0.2 to 5.0.

4. The surface-modified carbon material according to claim 1 or 2, wherein the carbon material is graphite, and Id/Ig of G-band intensities Ig and D-band intensities Id in raman spectra of the surface is 0.01 to 0.11.

5. A process for producing a surface-modified carbon material, comprising a step 1 of forming a thin film on the surface of a carbon material with an organic compound, and a step 2 of reacting an aryl compound with the surface of the carbon material using the thin film as a mask,

the aryl compound is a compound represented by the following formula (3),

[ chemical formula 2]

In the formula (3), R ¹ 、R ² And R is ³ Each independently is alkyl, alkenyl, alkynyl, aryl, OR, COOH, SOOH, SOONH ₂ 、NO ₂ 、COOR、SiR ₃ 、H、F、Cl、Br、I、OH、NH ₂ NHR, CN, CONHR or COH, wherein R is alkyl, alkenyl, alkynyl or aryl, Z is a halogen atom, BF ₄ 、BR ₄ Or PF (physical pattern) ₆ Wherein R is ₄ Is alkyl, alkenyl, alkynyl, aryl or halogen substituent thereof,

in the step 2, an aryl compound is reacted with the surface of the carbon material at a position of a gap between the periodic assembly.

6. The method for producing a surface-modified carbon material according to claim 5, wherein the linear alkane or linear alkane derivative is a compound represented by the following formula (2),

[ chemical formula 3]

In the formula (2), X represents H, CH ₃ 、CF ₃ 、CH＝CH ₂ C.ident.CH, aryl, F, cl, br, I, OH, SH, NH ₂ COH or COOH, Y representing CH ₂ 、CF ₂ Ch=ch, c≡c, 2-valent radical formed by removing 2 hydrogen atoms from aromatic hydrocarbon, O, S, NH, CO, COO, CONH, NHCO or NHCHX, Z represents H, CH ₃ Aryl, OH, SH, NH ₂ COH, COOH, COOX, CONH, NHCOX or NHCHX, n is 15-80 carbon atoms in alkane and alkane derivative satisfying formula (2)Is an integer of 10 to 80.

7. The method for producing a surface-modified carbon material as defined in claim 5 or 6, wherein the thin film is a monolayer.

8. A method for producing a surface-modified carbon material by electrochemically reacting an aryl compound with a carbon material using an electrochemical cell comprising a working electrode, a counter electrode, a reference electrode, and an aqueous electrolyte solution,

as the aqueous electrolyte solution, an aqueous solution containing the above aryl compound is used,

the aryl compound is a compound represented by the following formula (3),

[ chemical formula 4]

a liquid medium containing a compound exhibiting periodic self-assembly is disposed between the working electrode and the aqueous electrolyte solution, the aqueous electrolyte solution and the liquid medium being non-miscible with each other,

the compound exhibiting periodic self-assembly property is a linear alkane having 15 to 80 carbon atoms or a linear alkane derivative having 10 to 80 carbon atoms.

9. The method for producing a surface-modified carbon material according to claim 8, wherein the linear alkane or linear alkane derivative is a compound represented by the following formula (2),

[ chemical formula 5]

10. The method for producing a surface-modified carbon material according to claim 8 or 9, wherein the concentration of the alkane or the linear alkane derivative in the liquid medium is 1. Mu. Mol/L or more.

11. The method for producing a surface-modified carbon material as claimed in claim 8, wherein the linear alkane derivative is a dehydrobenzo [12] rotarene derivative.

12. The method for producing a surface-modified carbon material as defined in claim 8, wherein the liquid medium is obtained by dissolving the compound exhibiting periodic self-assembly in a nonpolar organic solvent or a low-polar organic solvent.

13. The method for producing a surface-modified carbon material as claimed in claim 12, wherein the nonpolar organic solvent or the low-polar organic solvent is a fatty acid, an alkyl-substituted benzene, an alkane having less than 20 carbon atoms, an alkanol, a dialkyl ether, a halogenated hydrocarbon or an aromatic hydrocarbon.

14. The method for producing a surface-modified carbon material as defined in claim 8, wherein a concentration of said aryl compound in said aqueous electrolyte solution is 0.2 to 10.0 mmol/L.

15. The surface-modified carbon material according to claim 1, wherein the two-dimensional periodic surface-modified carbon material is observed,

The surface is provided with 5-15 nm per subarea ² When dividing the area of (a), the ratio of the total number of the divided areas where aryl groups are present to the total number of the divided areas is 70% or more.

16. The surface-modified carbon material according to claim 15, wherein the proportion is 90% or more.

17. A field effect transistor comprising the surface-modified carbon material of any one of claims 1 to 4, 15 or 16.

18. A sensor comprising the surface-modified carbon material of any one of claims 1-4, 15, or 16.

19. A light-emitting element comprising the surface-modified carbon material according to any one of claims 1 to 4, 15 or 16.

20. A catalyst comprising the surface-modified carbon material according to any one of claims 1 to 4, 15 or 16.